Modified Human Growth Hormone Polypeptides and Their Uses

ABSTRACT

Modified human growth hormone polypeptides and uses thereof are provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. provisional patent applicationSer. No. 60/541,528, filed Feb. 2, 2004, U.S. provisional patentapplication Ser. No. 60/581,314, filed Jun. 18, 2004, U.S. provisionalpatent application Ser. No. 60/581,175, filed Jun. 18, 2004, U.S.provisional patent application Ser. No. 60/580,885, filed Jun. 18, 2004,and U.S. provisional patent application entitled 60/638,616 filed Dec.22, 2004, the specifications of which are incorporated herein in theirentirety.

FIELD OF THE INVENTION

This invention relates to growth hormone polypeptides modified with atleast one non-naturally-encoded amino acid.

BACKGROUND OF THE INVENTION

The growth hormone (GH) supergene family (Bazan, F. Immunology Today 11:350-354 (1991); Mott, H. R. and Campbell, I. D. Current Opinion inStructural Biology 5: 114-121 (1995); Silvennoinen, O. and Ihle, J. N.(1996) SIGNALING BY THE HEMATOPOIETIC CYTOKINE RECEPTORS) represents aset of proteins with similar structural characteristics. Each member ofthis family of proteins comprises a four helical bundle, the generalstructure of which is shown in FIG. 1. While there are still moremembers of the family yet to be identified, some members of the familyinclude the following: growth hormone, prolactin, placental lactogen,erythropoietin (EPO), thrombopoietin (TPO), interleukin-2 (IL-2), IL-3,IL-4, IL-5, IL-6, IL-7, IL-9, IL-10, IL-11, IL-12 (p35 subunit), IL-13,IL-15, oncostatin M, ciliary neurotrophic factor, leukemia inhibitoryfactor, alpha interferon, beta interferon, gamma interferon, omegainterferon, tau interferon, epsilon interferon, granulocyte-colonystimulating factor (G-CSF), granulocyte-macrophage colony stimulatingfactor (GM-CSF), macrophage colony stimulating factor (M-CSF) andcardiotrophin-1 (CT-1) (“the GH supergene family”). Members of the GHsupergene family have similar secondary and tertiary structures, despitethe fact that they generally have limited amino acid or DNA sequenceidentity. The shared structural features allow new members of the genefamily to be readily identified. The general structures of familymembers hGH, EPO, IFNα-2, and G-CSF are shown in FIGS. 2, 3, 4, and 5,respectively.

One member of the GH supergene family is human growth hormone (hGH).Human growth hormone participates in much of the regulation of normalhuman growth and development. This naturally-occurring single-chainpituitary hormone consists of 191 amino acid residues and has amolecular weight of approximately 22 kDa. hGH exhibits a multitude ofbiological effects, including linear growth (somatogenesis), lactation,activation of macrophages, and insulin-like and diabetogenic effects,among others (Chawla, R., et al., Ann. Rev. Med. 34:519-547 (1983);Isaksson, O., et al., Ann. Rev. Physiol., 47:483-499 (1985); Hughes, J.and Friesen, H., Ann. Rev. Physiol., 47:469-482 (1985)).

The structure of hGH is well known (Goeddel, D., et al., Nature281:544-548 (1979)), and the three-dimensional structure of hGH has beensolved by x-ray crystallography (de Vos, A., et al., Science 255:306-312(1992)). The protein has a compact globular structure, comprising fouramphipathic alpha helical bundles, termed A-D beginning from theN-terminus, which are joined by loops. hGH also contains four cysteineresidues, which participate in two intramolecular disulfide bonds: C53is paired with C165 and C182 is paired with C189. The hormone is notglycosylated and has been expressed in a secreted form in E. coli(Chang, C., et al., Gene 55:189-196 (1987)).

A number of naturally occurring mutants of hGH have been identified.These include hGH-V (Seeberg, DNA 1: 239 (1982); U.S. Pat. Nos.4,446,235, 4,670,393, and 4,665,180, which are incorporated by referenceherein) and a 20-kDa hGH containing a deletion of residues 32-46 of hGH(Kostyo et al., Biochem. Biophys. Acta 925: 314 (1987); Lewis, U., etal., J. Biol. Chem., 253:2679-2687 (1978)). In addition, numerous hGHvariants, arising from post-transcriptional, post-translational,secretory, metabolic processing, and other physiological processes, havebeen reported (Baumann, G., Endocrine Reviews 12: 424 (1991)).

The biological effects of hGH derive from its interaction with specificcellular receptors. The hormone is a member of a family of homologousproteins that include placental lactogens and prolactins. hGH is unusualamong the family members, however, in that it exhibits broad speciesspecificity and binds to either the cloned somatogenic (Leung, D., etal., Nature 330:537-543 (1987)) or prolactin (Boutin, J., et al., Cell53:69-77 (1988)) receptor. Based on structural and biochemical studies,functional maps for the lactogenic and somatogenic binding domains havebeen proposed (Cunningham, B. and Wells, J., Proc. Natl. Acad. Sci. 88:3407 (1991)). The hGH receptor is a member of thehematopoietic/cytokine/growth factor receptor family, which includesseveral other growth factor receptors, such as the interleukin (IL)-3,-4 and -6 receptors, the granulocyte macrophage colony-stimulatingfactor (GM-CSF) receptor, the erythropoietin (EPO) receptor, as well asthe G-CSF receptor. See, Bazan, Proc. Natl. Acad. Sci. USA 87: 6934-6938(1990). Members of the cytokine receptor family contain four conservedcysteine residues and a tryptophan-serine-X-tryptophan-serine motifpositioned just outside the transmembrane region. The conservedsequences are thought to be involved in protein-protein interactions.See, e.g., Chiba et al., Biochim. Biophys. Res. Comm. 184: 485-490(1992). The interaction between hGH and extracellular domain of itsreceptor (hGHbp) is among the most well understood hormone-receptorinteractions. High-resolution X-ray crystallographic data (Cunningham,B., et al., Science, 254:821-825 (1991)) has shown that hGH has tworeceptor binding sites and binds two receptor molecules sequentiallyusing distinct sites on the molecule. The two receptor binding sites arereferred to as Site I and Site II. Site I includes the carboxy terminalend of helix D and parts of helix A and the A-B loop, whereas Site IIencompasses the amino terminal region of helix A and a portion of helixC. Binding of GH to its receptor occurs sequentially, with Site Ibinding first. Site II then engages a second GH receptor, resulting inreceptor dimerization and activation of the intracellular signalingpathways that lead to cellular responses to the hormone. An hGH muteinin which a G120R substitution has been introduced into site II is ableto bind a single hGH receptor, but is unable to dimerize two receptors.The mutein acts as an hGH antagonist in vitro, presumably by occupyingreceptor sites without activating intracellular signaling pathways (Fuh,G., et al., Science 256:1677-1680 (1992)).

Recombinant hGH is used as a therapeutic and has been approved for thetreatment of a number of indications. hGH deficiency leads to dwarfism,for example, which has been successfully treated for more than a decadeby exogenous administration of the hormone. In addition to hGHdeficiency, hGH has also been approved for the treatment of renalfailure (in children), Turner's Syndrome, and cachexia in AIDS patients.Recently, the Food and Drug Administration (FDA) has approved hGH forthe treatment of non-GH-dependent short stature. hGH is also currentlyunder investigation for the treatment of aging, frailty in the elderly,short bowel syndrome, and congestive heart failure.

Recombinant hGH is currently sold as a daily injectable product, withfive major products currently on the market: Humatrope™ (Eli Lilly &Co.), Nutropin™ (Genentech), Norditropin™ (Novo-Nordisk), Genotropin™(Pfizer) and Saizen/Serostim™ (Serono). A significant challenge to usinggrowth hormone as a therapeutic, however, is that the protein has ashort in vivo half-life and, therefore, it must be administered by dailysubcutaneous injection for maximum effectiveness (MacGillivray, et al.,J. Clin. Endocrinol. Metab. 81: 1806-1809 (1996)). Considerable effortis focused on means to improve the administration of hGH agonists andantagonists, by lowering the cost of production, making administrationeasier for the patient, improving efficacy and safety profile, andcreating other properties that would provide a competitive advantage.For example, Genentech and Alkermes formerly marketed Nutropin Depot™, adepot formulation of hGH, for pediatric growth hormone deficiency. Whilethe depot permits less frequent administration (once every 2-3 weeksrather than once daily), it is also associated with undesirable sideeffects, such as decreased bioavailability and pain at the injectionsite and was withdrawn from the market in 2004. Another product,Pegvisomant™ (Pfizer), has also recently been approved by the FDA.Pegvisomant™ is a genetically-engineered analogue of hGH that functionsas a highly selective growth hormone receptor antagonist indicated forthe treatment of acromegaly (van der Lely, et al., The Lancet 358:1754-1759 (2001). Although several of the amino acid side chain residuesin Pegvisomant™ are derivatized with polyethylene glycol (PEG) polymers,the product is still administered once-daily, indicating that thepharmaceutical properties are not optimal. In addition to PEGylation anddepot formulations, other administration routes, including inhaled andoral dosage forms of hGH, are under early-stage pre-clinical andclinical development and none has yet received approval from the FDA.Accordingly, there is a need for a polypeptide that exhibits growthhormone activity but that also provides a longer serum half-life and,therefore, more optimal therapeutic levels of hGH and an increasedtherapeutic half-life.

Covalent attachment of the hydrophilic polymer poly(ethylene glycol),abbreviated PEG, is a method of increasing water solubility,bioavailability, increasing serum half-life, increasing therapeutichalf-life, modulating immunogenicity, modulating biological activity, orextending the circulation time of many biologically active molecules,including proteins, peptides, and particularly hydrophobic molecules.PEG has been used extensively in pharmaceuticals, on artificialimplants, and in other applications where biocompatibility, lack oftoxicity, and lack of immunogenicity are of importance. In order tomaximize the desired properties of PEG, the total molecular weight andhydration state of the PEG polymer or polymers attached to thebiologically active molecule must be sufficiently high to impart theadvantageous characteristics typically associated with PEG polymerattachment, such as increased water solubility and circulating halflife, while not adversely impacting the bioactivity of the parentmolecule.

PEG derivatives are frequently linked to biologically active moleculesthrough reactive chemical functionalities, such as lysine, cysteine andhistidine residues, the N-terminus and carbohydrate moieties. Proteinsand other molecules often have a limited number of reactive sitesavailable for polymer attachment. Often, the sites most suitable formodification via polymer attachment play a significant role in receptorbinding, and are necessary for retention of the biological activity ofthe molecule. As a result, indiscriminate attachment of polymer chainsto such reactive sites on a biologically active molecule often leads toa significant reduction or even total loss of biological activity of thepolymer-modified molecule. R. Clark et al., (1996), J. Biol. Chem.,271:21969-21977. To form conjugates having sufficient polymer molecularweight for imparting the desired advantages to a target molecule, priorart approaches have typically involved random attachment of numerouspolymer arms to the molecule, thereby increasing the risk of a reductionor even total loss in bioactivity of the parent molecule.

Reactive sites that form the loci for attachment of PEG derivatives toproteins are dictated by the protein's structure. Proteins, includingenzymes, are composed of various sequences of alpha-amino acids, whichhave the general structure H₂N—CHR—COOH. The alpha amino moiety (H₂N—)of one amino acid joins to the carboxyl moiety (—COOH) of an adjacentamino acid to form amide linkages, which can be represented as—(NH—CHR—CO)_(n)—, where the subscript “n” can equal hundreds orthousands. The fragment represented by R can contain reactive sites forprotein biological activity and for attachment of PEG derivatives.

For example, in the case of the amino acid lysine, there exists an —NH₂moiety in the epsilon position as well as in the alpha position. Theepsilon —NH₂ is free for reaction under conditions of basic pH. Much ofthe art in the field of protein derivatization with PEG has beendirected to developing PEG derivatives for attachment to the epsilon—NH₂ moiety of lysine residues present in proteins. “Polyethylene Glycoland Derivatives for Advanced PEGylation”, Nektar Molecular EngineeringCatalog, 2003, pp. 1-17. These PEG derivatives all have the commonlimitation, however, that they cannot be installed selectively among theoften numerous lysine residues present on the surfaces of proteins. Thiscan be a significant limitation in instances where a lysine residue isimportant to protein activity, existing in an enzyme active site forexample, or in cases where a lysine residue plays a role in mediatingthe interaction of the protein with other biological molecules, as inthe case of receptor binding sites.

A second and equally important complication of existing methods forprotein PEGylation is that the PEG derivatives can undergo undesiredside reactions with residues other than those desired. Histidinecontains a reactive imino moiety, represented structurally as —N(H)—,but many chemically reactive species that react with epsilon —NH₂ canalso react with —N(H)—. Similarly, the side chain of the amino acidcysteine bears a free sulfhydryl group, represented structurally as —SH.In some instances, the PEG derivatives directed at the epsilon —NH₂group of lysine also react with cysteine, histidine or other residues.This can create complex, heterogeneous mixtures of PEG-derivatizedbioactive molecules and risks destroying the activity of the bioactivemolecule being targeted. It would be desirable to develop PEGderivatives that permit a chemical functional group to be introduced ata single site within the protein that would then enable the selectivecoupling of one or more PEG polymers to the bioactive molecule atspecific sites on the protein surface that are both well-defined andpredictable.

In addition to lysine residues, considerable effort in the art has beendirected toward the development of activated PEG reagents that targetother amino acid side chains, including cysteine, histidine and theN-terminus. See, e.g., U.S. Pat. No. 6,610,281 which is incorporated byreference herein, and “Polyethylene Glycol and Derivatives for AdvancedPEGylation”, Nektar Molecular Engineering Catalog, 2003, pp. 1-17. Acysteine residue can be introduced site-selectively into the structureof proteins using site-directed mutagenesis and other techniques knownin the art, and the resulting free sulfhydryl moiety can be reacted withPEG derivatives that bear thiol-reactive functional groups. Thisapproach is complicated, however, in that the introduction of a freesulfhydryl group can complicate the expression, folding and stability ofthe resulting protein. Thus, it would be desirable to have a means tointroduce a chemical functional group into bioactive molecules thatenables the selective coupling of one or more PEG polymers to theprotein while simultaneously being compatible with (i.e., not engagingin undesired side reactions with) sulfhydryls and other chemicalfunctional groups typically found in proteins.

As can be seen from a sampling of the art, many of these derivativesthat have been developed for attachment to the side chains of proteins,in particular, the —NH₂ moiety on the lysine amino acid side chain andthe —SH moiety on the cysteine side chain, have proven problematic intheir synthesis and use. Some form unstable linkages with the proteinthat are subject to hydrolysis and therefore decompose, degrade, or areotherwise unstable in aqueous environments, such as in the bloodstream.Some form more stable linkages, but are subject to hydrolysis before thelinkage is formed, which means that the reactive group on the PEGderivative may be inactivated before the protein can be attached. Someare somewhat toxic and are therefore less suitable for use in vivo. Someare too slow to react to be practically useful. Some result in a loss ofprotein activity by attaching to sites responsible for the protein'sactivity. Some are not specific in the sites to which they will attach,which can also result in a loss of desirable activity and in a lack ofreproducibility of results. In order to overcome the challengesassociated with modifying proteins with poly(ethylene glycol) moieties,PEG derivatives have been developed that are more stable (e.g., U.S.Pat. No. 6,602,498, which is incorporated by reference herein) or thatreact selectively with thiol moieties on molecules and surfaces (e.g.,U.S. Pat. No. 6,610,281, which is incorporated by reference herein).There is clearly a need in the art for PEG derivatives that arechemically inert in physiological environments until called upon toreact selectively to form stable chemical bonds.

Recently, an entirely new technology in the protein sciences has beenreported, which promises to overcome many of the limitations associatedwith site-specific modifications of proteins. Specifically, newcomponents have been added to the protein biosynthetic machinery of theprokaryote Escherichia coli (E. coli) (e.g., L. Wang, et al., (2001),Science 292:498-500) and the eukaryote Sacchromyces cerevisiae (S.cerevisiae) (e.g., J. Chin et al., Science 301:964-7 (2003)), which hasenabled the incorporation of non-genetically encoded amino acids toproteins in vivo. A number of new amino acids with novel chemical,physical or biological properties, including photoaffinity labels andphotoisomerizable amino acids, keto amino acids, and glycosylated aminoacids have been incorporated efficiently and with high fidelity intoproteins in E. coli and in yeast in response to the amber codon, TAG,using this methodology. See, e.g., J. W. Chin et al., (2002), Journal ofthe American Chemical Society 124:9026-9027; J. W. Chin, & P. G.Schultz, (2002), ChemBioChem 11:1135-1137; J. W. Chin, et al., (2002),PNAS United States of America 99:11020-11024; and, L. Wang, & P. G.Schultz, (2002), Chem. Comm., 1-10. These studies have demonstrated thatit is possible to selectively and routinely introduce chemicalfunctional groups, such as ketone groups, alkyne groups and azidemoieties, that are not found in proteins, that are chemically inert toall of the functional groups found in the 20 common, genetically-encodedamino acids and that may be used to react efficiently and selectively toform stable covalent linkages.

The ability to incorporate non-genetically encoded amino acids intoproteins permits the introduction of chemical functional groups thatcould provide valuable alternatives to the naturally-occurringfunctional groups, such as the epsilon —NH₂ of lysine, the sulfhydryl—SH of cysteine, the imino group of histidine, etc. Certain chemicalfunctional groups are known to be inert to the functional groups foundin the 20 common, genetically-encoded amino acids but react cleanly andefficiently to form stable linkages. Azide and acetylene groups, forexample, are known in the art to undergo a Huisgen [3+2] cycloadditionreaction in aqueous conditions in the presence of a catalytic amount ofcopper. See, e.g., Tornoe, et al., (2002) Org. Chem. 67:3057-3064; and,Rostovtsev, et al., (2002) Angew. Chem. Int. Ed. 41:2596-2599. Byintroducing an azide moiety into a protein structure, for example, oneis able to incorporate a functional group that is chemically inert toamines, sulfhydryls, carboxylic acids, hydroxyl groups found inproteins, but that also reacts smoothly and efficiently with anacetylene moiety to form a cycloaddition product. Importantly, in theabsence of the acetylene moiety, the azide remains chemically inert andunreactive in the presence of other protein side chains and underphysiological conditions.

The present invention addresses, among other things, problems associatedwith the activity and production of GH polypeptides, and also addressesthe production of a hGH polypeptide with improved biological orpharmacological properties, such as improved therapeutic half-life.

BRIEF SUMMARY OF THE INVENTION

This invention provides GH supergene family members, including hGHpolypeptides, comprising one or more non-naturally encoded amino acids.

In some embodiments, the hGH polypeptide comprises one or morepost-translational modifications. In some embodiments, the hGHpolypeptide is linked to a linker, polymer, or biologically activemolecule. In some embodiments, the hGH polypeptide is linked to abifunctional polymer, bifunctional linker, or at least one additionalhGH polypeptide.

In some embodiments, the non-naturally encoded amino acid is linked to awater soluble polymer. In some embodiments, the water soluble polymercomprises a poly(ethylene glycol) moiety. In some embodiments, thepoly(ethylene glycol) molecule is a bifunctional polymer. In someembodiments, the bifunctional polymer is linked to a second polypeptide.In some embodiments, the second polypeptide is a hGH polypeptide.

In some embodiments, the hGH polypeptide comprises at least two aminoacids linked to a water soluble polymer comprising a poly(ethyleneglycol) moiety. In some embodiments, at least one amino acid is anon-naturally encoded amino acid.

Regions of hGH can be illustrated as follows, wherein the amino acidpositions in hGH are indicated in the middle row:

In some embodiments, one or more non-naturally encoded amino acids areincorporated at any position in one or more of the following regionscorresponding to secondary structures in hGH as follows: 1-5(N-terminus), 6-33 (A helix), 34-74 (region between A helix and B helix,the A-B loop), 75-96 (B helix), 97-105 (region between B helix and Chelix, the B-C loop), 106-129 (C helix), 130-153 (region between C helixand D helix, the C-D loop), 154-183 (D helix), 184-191 (C-terminus) fromSEQ ID NO: 2 or the corresponding amino acids of SEQ ID NO: 1 or 3. Inother embodiments, the non-naturally encoded amino acid is substitutedat a position selected from the group consisting of residues 1-5, 32-46,97-105, 132-149, and 184-191 from hGH SEQ ID NO: 2 or the correspondingamino acids of SEQ ID NO: 1 or 3. In some embodiments, one or morenon-naturally encoded amino acids are incorporated in one or more of thefollowing positions in hGH: before position 1 (i.e. at the N-terminus),1, 2, 3, 4, 5, 8, 9, 11, 12, 15, 16, 19, 22, 29, 30, 32, 33, 34, 35, 36,37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 52, 55, 57, 59, 65,66, 69, 70, 71, 74, 88, 91, 92, 94, 95, 97, 98, 99, 100, 101, 102, 103,104, 105, 106, 107, 108, 109, 111, 112, 113, 115, 116, 119, 120, 122,123, 126, 127, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139,140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153,154, 155, 156, 158, 159, 161, 168, 172, 183, 184, 185, 186, 187, 188,189, 190, 191, 192 (i.e., at the carboxyl terminus of the protein) (SEQID NO: 2 or the corresponding amino acids of SEQ ID NO: 1 or 3).

In some embodiments, one or more non-naturally encoded amino acids aresubstituted at one or more of the following positions: 29, 30, 33, 34,35, 37, 39, 40, 49, 57, 59, 66, 69, 70, 71, 74, 88, 91, 92, 94, 95, 98,99, 101, 103, 107, 108, 111, 122, 126, 129, 130, 131, 133, 134, 135,136, 137, 139, 140, 141, 142, 143, 145, 147, 154, 155, 156, 159, 183,186, and 187 (SEQ ID NO: 2 or the corresponding amino acids of SEQ IDNO: 1 or 3).

In some embodiments, one or more non-naturally encoded amino acids aresubstituted at one or more of the following positions: 29, 33, 35, 37,39, 49, 57, 69, 70, 71, 74, 88, 91, 92, 94, 95, 98, 99, 101, 103, 107,108, 111, 129, 130, 131, 133, 134, 135, 136, 137, 139, 140, 141, 142,143, 145, 147, 154, 155, 156, 186, and 187 (SEQ ID NO: 2 or thecorresponding amino acids of SEQ ID NO: 1 or 3).

In some embodiments, one or more non-naturally encoded amino acids aresubstituted at one or more of the following positions: 35, 88, 91, 92,94, 95, 99, 101, 103, 111, 131, 133, 134, 135, 136, 139, 140, 143, 145,and 155 (SEQ ID NO: 2 or the corresponding amino acids of SEQ ID NO: 1or 3).

In some embodiments, one or more non-naturally encoded amino acids aresubstituted at one or more of the following positions: 30, 74, 103 (SEQID NO: 2 or the corresponding amino acids of SEQ ID NO: 1 or 3). In someembodiments, one or more non-naturally encoded amino acids aresubstituted at one or more of the following positions: 35, 92, 143, 145(SEQ ID NO: 2 or the corresponding amino acids of SEQ ID NO: 1 or 3).

In some embodiments, the non-naturally occurring amino acid at one ormore of these positions is linked to a water soluble polymer, includingbut not limited to, positions: before position 1 (i.e. at theN-terminus), 1, 2, 3, 4, 5, 8, 9, 11, 12, 15, 16, 19, 22, 29, 30, 32,33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 52,55, 57, 59, 65, 66, 69, 70, 71, 74, 88, 91, 92, 94, 95, 97, 98, 99, 100,101, 102, 103, 104, 105, 106, 107, 108, 109, 111, 112, 113, 115, 116,119, 120, 122, 123, 126, 127, 129, 130, 131, 132, 133, 134, 135, 136,137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150,151, 152, 153, 154, 155, 156, 158, 159, 161, 168, 172, 183, 184, 185,186, 187, 188, 189, 190, 191, 192 (i.e., at the carboxyl terminus of theprotein) (SEQ ID NO: 2 or the corresponding amino acids of SEQ ID NO: 1or 3). In some embodiments, the non-naturally occurring amino acid atone or more of these positions is linked to a water soluble polymer: 30,35, 74, 92, 103, 143, 145 (SEQ ID NO: 2 or the corresponding amino acidsof SEQ ID NO: 1 or 3). In some embodiments, the non-naturally occurringamino acid at one or more of these positions is linked to a watersoluble polymer: 35, 92, 143, 145 (SEQ ID NO: 2 or the correspondingamino acids of SEQ ID NO: 1 or 3).

Human GH antagonists include, but are not limited to, those withsubstitutions at: 1, 2, 3, 4, 5, 8, 9, 11, 12, 15, 16, 19, 22, 103, 109,112, 113, 115, 116, 119, 120, 123, and 127 or an addition at position 1(i.e., at the N-terminus), or any combination thereof (SEQ ID NO:2, orthe corresponding amino acid in SEQ ID NO: 1, 3, or any other GHsequence).

In some embodiments, the hGH polypeptide comprises a substitution,addition or deletion that modulates affinity of the hGH polypeptide fora hGH polypeptide receptor. In some embodiments, the hGH polypeptidecomprises a substitution, addition, or deletion that increases thestability of the hGH polypeptide. In some embodiments, the hGHpolypeptide comprises an amino acid substitution selected from the groupconsisting of F10A, F10H, F10I; M14W, M14Q, M14G; H18D; H21N; G120A;R167N; D171S; E174S; F176Y, I179T or any combination thereof in hGH SEQID NO: 2. In some embodiments, the hGH polypeptide comprises asubstitution, addition, or deletion that modulates the immunogenicity ofthe hGH polypeptide. In some embodiments, the hGH polypeptide comprisesa substitution, addition, or deletion that modulates serum half-life orcirculation time of the hGH polypeptide.

In some embodiments, the hGH polypeptide comprises a substitution,addition, or deletion that increases the aqueous solubility of the hGHpolypeptide. In some embodiments, the hGH polypeptide comprises asubstitution, addition, or deletion that increases the solubility of thehGH polypeptide produced in a host cell. In some embodiments, the hGHpolypeptide comprises a substitution, addition, or deletion thatincreases the expression of the hGH polypeptide in a host cell orsynthesized in vitro. In some embodiments, the hGH polypeptide comprisesan amino acid substitution G120A. The hGH polypeptide comprising thissubstitution retains agonist activity and retains or improves expressionlevels in a host cell. In some embodiments, the hGH polypeptidecomprises a substitution, addition, or deletion that increases proteaseresistance of the hGH polypeptide.

In some embodiments the amino acid substitutions in the hGH polypeptidemay be with naturally occurring or non-naturally occurring amino acids,provided that at least one substitution is with a non-naturally encodedamino acid.

In some embodiments, the non-naturally encoded amino acid comprises acarbonyl group, an aminooxy group, a hydrazine group, a hydrazide group,a semicarbazide group, an azide group, or an alkyne group.

In some embodiments, the non-naturally encoded amino acid comprises acarbonyl group. In some embodiments, the non-naturally encoded aminoacid has the structure:

wherein n is 0-10; R₁ is an alkyl, aryl, substituted alkyl, orsubstituted aryl; R₂ is H, an alkyl, aryl, substituted alkyl, andsubstituted aryl; and R₃ is H, an amino acid, a polypeptide, or an aminoterminus modification group, and R₄ is H, an amino acid, a polypeptide,or a carboxy terminus modification group.

In some embodiments, the non-naturally encoded amino acid comprises anaminooxy group. In some embodiments, the non-naturally encoded aminoacid comprises a hydrazide group. In some embodiments, the non-naturallyencoded amino acid comprises a hydrazine group. In some embodiments, thenon-naturally encoded amino acid residue comprises a semicarbazidegroup.

In some embodiments, the non-naturally encoded amino acid residuecomprises an azide group. In some embodiments, the non-naturally encodedamino acid has the structure:

wherein n is 0-10; R₁ is an alkyl, aryl, substituted alkyl, substitutedaryl or not present; X is O, N, S or not present; m is 0-10; R₂ is H, anamino acid, a polypeptide, or an amino terminus modification group, andR₃ is H, an amino acid, a polypeptide, or a carboxy terminusmodification group.

In some embodiments, the non-naturally encoded amino acid comprises analkyne group. In some embodiments, the non-naturally encoded amino acidhas the structure:

wherein n is 0-10; R₁ is an alkyl, aryl, substituted alkyl, orsubstituted aryl; X is O, N, S or not present; m is 0-10, R₂ is H, anamino acid, a polypeptide, or an amino terminus modification group, andR₃ is H, an amino acid, a polypeptide, or a carboxy terminusmodification group.

In some embodiments, the polypeptide is a hGH polypeptide agonist,partial agonist, antagonist, partial antagonist, or inverse agonist. Insome embodiments, the hGH polypeptide agonist, partial agonist,antagonist, partial antagonist, or inverse agonist comprises anon-naturally encoded amino acid linked to a water soluble polymer. Insome embodiments, the water soluble polymer comprises a poly(ethyleneglycol) moiety. In some embodiments, the hGH polypeptide agonist,partial agonist, antagonist, partial antagonist, or inverse agonistcomprises a non-naturally encoded amino acid and one or morepost-translational modification, linker, polymer, or biologically activemolecule. In some embodiments, the non-naturally encoded amino acidlinked to a water soluble polymer is present within the Site II region(the region of the protein encompassing the AC helical-bundle face,amino terminal region of helix A and a portion of helix C) of the hGHpolypeptide. In some embodiments, the hGH polypeptide comprising anon-naturally encoded amino acid linked to a water soluble polymerprevents dimerization of the hGH polypeptide receptor by preventing thehGH polypeptide antagonist from binding to a second hGH polypeptidereceptor molecule. In some embodiments, an amino acid other than glycineis substituted for G120 in SEQ ID NO: 2 (hGH). In some embodiments,arginine is substituted for G120 in SEQ ID NO: 2. In some embodiments, anon-naturally encoded amino acid is substituted for G120 in SEQ ID NO:2.

The present invention also provides isolated nucleic acids comprising apolynucleotide that hybridizes under stringent conditions to SEQ ID NO:21 or 22 wherein the polynucleotide comprises at least one selectorcodon. In some embodiments, the selector codon is selected from thegroup consisting of an amber codon, ochre codon, opal codon, a uniquecodon, a rare codon, and a four-base codon.

The present invention also provides methods of making a hGH polypeptidelinked to a water soluble polymer. In some embodiments, the methodcomprises contacting an isolated hGH polypeptide comprising anon-naturally encoded amino acid with a water soluble polymer comprisinga moiety that reacts with the non-naturally encoded amino acid. In someembodiments, the non-naturally encoded amino acid incorporated into thehGH polypeptide is reactive toward a water soluble polymer that isotherwise unreactive toward any of the 20 common amino acids. In someembodiments, the non-naturally encoded amino acid incorporated into thehGH polypeptide is reactive toward a linker, polymer, or biologicallyactive molecule that is otherwise unreactive toward any of the 20 commonamino acids.

In some embodiments, the hGH polypeptide linked to the water solublepolymer is made by reacting a hGH polypeptide comprising acarbonyl-containing amino acid with a poly(ethylene glycol) moleculecomprising an aminooxy, hydrazine, hydrazide or semicarbazide group. Insome embodiments, the aminooxy, hydrazine, hydrazide or semicarbazidegroup is linked to the poly(ethylene glycol) molecule through an amidelinkage.

In some embodiments, the hGH polypeptide linked to the water solublepolymer is made by reacting a poly(ethylene glycol) molecule comprisinga carbonyl group with a polypeptide comprising a non-naturally encodedamino acid that comprises an aminooxy, hydrazine, hydrazide orsemicarbazide group.

In some embodiments, the hGH polypeptide linked to the water solublepolymer is made by reacting a hGH polypeptide comprising analkyne-containing amino acid with a poly(ethylene glycol) moleculecomprising an azide moiety. In some embodiments, the azide or alkynegroup is linked to the poly(ethylene glycol) molecule through an amidelinkage.

In some embodiments, the hGH polypeptide linked to the water solublepolymer is made by reacting a hGH polypeptide comprising anazide-containing amino acid with a poly(ethylene glycol) moleculecomprising an alkyne moiety. In some embodiments, the azide or alkynegroup is linked to the poly(ethylene glycol) molecule through an amidelinkage.

In some embodiments, the poly(ethylene glycol) molecule has a molecularweight of between about 0.1 kDa and about 100 kDa. In some embodiments,the poly(ethylene glycol) molecule has a molecular weight of between 0.1kDa and 50 kDa.

In some embodiments, the poly(ethylene glycol) molecule is a branchedpolymer. In some embodiments, each branch of the poly(ethylene glycol)branched polymer has a molecular weight of between 1 kDa and 100 kDa, orbetween 1 kDa and 50 kDa.

In some embodiments, the water soluble polymer linked to the hGHpolypeptide comprises a polyalkylene glycol moiety. In some embodiments,the non-naturally encoded amino acid residue incorporated into the hGHpolypeptide comprises a carbonyl group, an aminooxy group, a hydrazidegroup, a hydrazine, a semicarbazide group, an azide group, or an alkynegroup. In some embodiments, the non-naturally encoded amino acid residueincorporated into the hGH polypeptide comprises a carbonyl moiety andthe water soluble polymer comprises an aminooxy, hydrazide, hydrazine,or semicarbazide moiety. In some embodiments, the non-naturally encodedamino acid residue incorporated into the hGH polypeptide comprises analkyne moiety and the water soluble polymer comprises an azide moiety.In some embodiments, the non-naturally encoded amino acid residueincorporated into the hGH polypeptide comprises an azide moiety and thewater soluble polymer comprises an alkyne moiety.

The present invention also provides compositions comprising a hGHpolypeptide comprising a non-naturally-encoded amino acid and apharmaceutically acceptable carrier. In some embodiments, thenon-naturally encoded amino acid is linked to a water soluble polymer.

The present invention also provides cells comprising a polynucleotideencoding the hGH polypeptide comprising a selector codon. In someembodiments, the cells comprise an orthogonal RNA synthetase and/or anorthogonal tRNA for substituting a non-naturally encoded amino acid intothe hGH polypeptide.

The present invention also provides methods of making a hGH polypeptidecomprising a non-naturally encoded amino acid. In some embodiments, themethods comprise culturing cells comprising a polynucleotide orpolynucleotides encoding a hGH polypeptide, an orthogonal RNA synthetaseand/or an orthogonal tRNA under conditions to permit expression of thehGH polypeptide; and purifying the hGH polypeptide from the cells and/orculture medium.

The present invention also provides methods of increasing therapeutichalf-life, serum half-life or circulation time of hGH polypeptides. Thepresent invention also provides methods of modulating immunogenicity ofhGH polypeptides. In some embodiments, the methods comprise substitutinga non-naturally encoded amino acid for any one or more amino acids innaturally occurring hGH polypeptides and/or linking the hGH polypeptideto a linker, a polymer, a water soluble polymer, or a biologicallyactive molecule.

The present invention also provides methods of treating a patient inneed of such treatment with an effective amount of a hGH molecule of thepresent invention. In some embodiments, the methods compriseadministering to the patient a therapeutically-effective amount of apharmaceutical composition comprising a hGH polypeptide comprising anon-naturally-encoded amino acid and a pharmaceutically acceptablecarrier. In some embodiments, the non-naturally encoded amino acid islinked to a water soluble polymer.

The present invention also provides hGH polypeptides comprising asequence shown in SEQ ID NO: 1, 2, 3, or any other GH polypeptidesequence, except that at least one amino acid is substituted by anon-naturally encoded amino acid. In some embodiments, the non-naturallyencoded amino acid is linked to a water soluble polymer. In someembodiments, the water soluble polymer comprises a poly(ethylene glycol)moiety. In some embodiments, the non-naturally encoded amino acidcomprises a carbonyl group, an aminooxy group, a hydrazide group, ahydrazine group, a semicarbazide group, an azide group, or an alkynegroup. In some embodiments, the non-naturally encoded amino acid issubstituted at a position selected from the group consisting of residues1-5, 82-90, 117-134, and 169-176 from SEQ ID NO: 3 (hGH).

The present invention also provides pharmaceutical compositionscomprising a pharmaceutically acceptable carrier and a hGH polypeptidecomprising the sequence shown in SEQ ID NO: 1, 2, 3, or any other GHpolypeptide sequence, wherein at least one amino acid is substituted bya non-naturally encoded amino acid. In some embodiments, thenon-naturally encoded amino acid comprises a saccharide moiety. In someembodiments, the water soluble polymer is linked to the polypeptide viaa saccharide moiety. In some embodiments, a linker, polymer, orbiologically active molecule is linked to the hGH polypeptide via asaccharide moiety.

The present invention also provides a hGH polypeptide comprising a watersoluble polymer linked by a covalent bond to the hGH polypeptide at asingle amino acid. In some embodiments, the water soluble polymercomprises a poly(ethylene glycol) moiety. In some embodiments, the aminoacid covalently linked to the water soluble polymer is a non-naturallyencoded amino acid present in the polypeptide. In some embodiments thenon-naturally encoded amino acid is substituted at position 35, 92, 143,or 145.

The present invention provides a hGH polypeptide comprising at least onelinker, polymer, or biologically active molecule, wherein said linker,polymer, or biologically active molecule is attached to the polypeptidethrough a functional group of a non-naturally encoded amino acidribosomally incorporated into the polypeptide. In some embodiments, thepolypeptide is monoPEGylated. The present invention also provides a hGHpolypeptide comprising a linker, polymer, or biologically activemolecule that is attached to one or more non-naturally encoded aminoacid wherein said non-naturally encoded amino acid is ribosomallyincorporated into the polypeptide at pre-selected sites.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1—A diagram of the general structure for four helical bundleproteins is shown.

FIG. 2—A diagram of the general structure for the four helical bundleprotein Growth Hormone (GH) is shown.

FIG. 3—A diagram of the general structure for the four helical bundleprotein Erythropoietin (EPO) is shown.

FIG. 4—A diagram of the general structure for the four helical bundleprotein Interferon alpha-2 (IFNα-2) is shown.

FIG. 5—A diagram of the general structure for the four helical bundleprotein Granulocyte Colony Stimulating Factor (G-CSF) is shown.

FIG. 6—A Coomassie blue stained SDS-PAGE is shown demonstrating theexpression of hGH comprising the non-naturally encoded amino acidp-acetyl phenylalanine at each of the following positions: Y35, F92,Y111, G131, R134, K140, Y143, or K145.

FIG. 7, Panels A and B—A diagram of the biological activity of the hGHcomprising a non-naturally encoded amino acid (Panel B) and wild-typehGH (Panel A) on IM9 cells is shown.

FIG. 8—A Coomassie blue stained SDS-PAGE is shown demonstrating theproduction of hGH comprising a non-naturally encoded amino acid that isPEGylated by covalent linkage of PEG (5, 20 and 30 kDa) to thenon-naturally encoded amino acid.

FIG. 9—A diagram is shown demonstrating the biological activity of thevarious PEGylated forms of hGH comprising a non-naturally encoded aminoacid on IM9 cells.

FIG. 10, Panel A—This figure depicts the primary structure of hGH withthe trypsin cleavage sites indicated and the non-natural amino acidsubstitution, F92pAF, specified with an arrow (Figure modified fromBecker et al. Biotechnol Appl Biochem. (1988) 10(4):326-337). FIG. 10,Panel B—Superimposed tryptic maps are shown of peptides generated from ahGH polypeptide comprising a non-naturally encoded amino acid that isPEGylated (labeled A), peptides generated from a hGH polypeptidecomprising a non-naturally encoded amino acid (labeled B), and peptidesgenerated from WHO rhGH (labeled C). FIG. 10, Panel C—A magnification ofpeak 9 from Panel B is shown.

FIG. 11, Panel A and Panel B show Coomassie blue stained SDS-PAGEanalysis of purified PEG-hGH polypeptides.

FIG. 12—A diagram of the biological activity of a hGH dimer molecule onIM9 cells is shown.

FIG. 13, Panel A—A diagram is shown of the IM-9 assay data measuringphosphorylation of pSTAT5 by hGH antagonist with the G120R substitution.FIG. 13, Panel B—A diagram is shown of the IM-9 assay data measuringphosphorylation of pSTAT5 by a hGH polypeptide with a non-natural aminoacid incorporated at the same position (G120).

FIG. 14—A diagram is shown indicating that a dimer of the hGH antagonistshown in FIG. 13, Panel B also lacks biological activity in the IM-9assay.

FIG. 15—A diagram is shown comparing the serum half-life in rats of hGHpolypeptide comprising a non-naturally encoded amino acid that isPEGylated with hGH polypeptide that is not PEGylated.

FIG. 16—A diagram is shown comparing the serum half-life in rats of hGHpolypeptides comprising a non-naturally encoded amino acid that isPEGylated.

FIG. 17—A diagram is shown comparing the serum half-life in rats of hGHpolypeptides comprising a non-naturally encoded amino acid that isPEGylated. Rats were dosed once with 2.1 mg/kg.

FIG. 18, Panel A—A diagram is shown of the effect on rat body weightgain after administration of a single dose of hGH polypeptidescomprising a non-naturally encoded amino acid that is PEGylated(position 35, 92). FIG. 18, Panel B—A diagram is shown of the effect oncirculating plasma IGF-1 levels after administration of a single dose ofhGH polypeptides comprising a non-naturally encoded amino acid that isPEGylated (position 35, 92). FIG. 18, Panel C—A diagram is shown of theeffect on rat body weight gain after administration of a single dose ofhGH polypeptides comprising a non-naturally encoded amino acid that isPEGylated (position 92, 134, 145, 131, 143). FIG. 18, Panel D—A diagramis shown of the effect on circulating plasma IGF-1 levels afteradministration of a single dose of hGH polypeptides comprising anon-naturally encoded amino acid that is PEGylated (position 92, 134,145, 131, 143). FIG. 18, Panel E—A diagram is shown comparing the serumhalf-life in rats of hGH polypeptides comprising a non-naturally encodedamino acid that is PEGylated (position 92, 134, 145, 131, 143).

DEFINITIONS

It is to be understood that this invention is not limited to theparticular methodology, protocols, cell lines, constructs, and reagentsdescribed herein and as such may vary. It is also to be understood thatthe terminology used herein is for the purpose of describing particularembodiments only, and is not intended to limit the scope of the presentinvention, which will be limited only by the appended claims.

As used herein and in the appended claims, the singular forms “a,” “an,”and “the” include plural reference unless the context clearly indicatesotherwise. Thus, for example, reference to a “hGH” is a reference to oneor more such proteins and includes equivalents thereof known to thoseskilled in the art, and so forth.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood to one of ordinary skill inthe art to which this invention belongs. Although any methods, devices,and materials similar or equivalent to those described herein can beused in the practice or testing of the invention, the preferred methods,devices and materials are now described.

All publications and patents mentioned herein are incorporated herein byreference for the purpose of describing and disclosing, for example, theconstructs and methodologies that are described in the publications,which might be used in connection with the presently describedinvention. The publications discussed herein are provided solely fortheir disclosure prior to the filing date of the present application.Nothing herein is to be construed as an admission that the inventors arenot entitled to antedate such disclosure by virtue of prior invention orfor any other reason.

The term “substantially purified” refers to a hGH polypeptide that maybe substantially or essentially free of components that normallyaccompany or interact with the protein as found in its naturallyoccurring environment, i.e. a native cell, or host cell in the case ofrecombinantly produced hGH polypeptides. hGH polypeptide that may besubstantially free of cellular material includes preparations of proteinhaving less than about 30%, less than about 25%, less than about 20%,less than about 15%, less than about 10%, less than about 5%, less thanabout 4%, less than about 3%, less than about 2%, or less than about 1%(by dry weight) of contaminating protein. When the hGH polypeptide orvariant thereof is recombinantly produced by the host cells, the proteinmay be present at about 30%, about 25%, about 20%, about 15%, about 10%,about 5%, about 4%, about 3%, about 2%, or about 1% or less of the dryweight of the cells. When the hGH polypeptide or variant thereof isrecombinantly produced by the host cells, the protein may be present inthe culture medium at about 5 g/L, about 4 g/L, about 3 g/L, about 2g/L, about 1 g/L, about 750 mg/L, about 500 mg/L, about 250 mg/L, about100 mg/L, about 50 mg/L, about 10 mg/L, or about 1 mg/L or less of thedry weight of the cells. Thus, “substantially purified” hGH polypeptideas produced by the methods of the present invention may have a puritylevel of at least about 30%, at least about 35%, at least about 40%, atleast about 45%, at least about 50%, at least about 55%, at least about60%, at least about 65%, at least about 70%, specifically, a puritylevel of at least about 75%, 80%, 85%, and more specifically, a puritylevel of at least about 90%, a purity level of at least about 95%, apurity level of at least about 99% or greater as determined byappropriate methods such as SDS/PAGE analysis, RP-HPLC, SEC, andcapillary electrophoresis.

A “recombinant host cell” or “host cell” refers to a cell that includesan exogenous polynucleotide, regardless of the method used forinsertion, for example, direct uptake, transduction, f-mating, or othermethods known in the art to create recombinant host cells. The exogenouspolynucleotide may be maintained as a nonintegrated vector, for example,a plasmid, or alternatively, may be integrated into the host genome.

As used herein, the term “medium” or “media” includes any culturemedium, solution, solid, semi-solid, or rigid support that may supportor contain any host cell, including bacterial host cells, yeast hostcells, insect host cells, plant host cells, eukaryotic host cells,mammalian host cells, CHO cells or E. coli, and cell contents. Thus, theterm may encompass medium in which the host cell has been grown, e.g.,medium into which the hGH polypeptide has been secreted, includingmedium either before or after a proliferation step. The term also mayencompass buffers or reagents that contain host cell lysates, such as inthe case where the hGH polypeptide is produced intracellularly and thehost cells are lysed or disrupted to release the hGH polypeptide.

“Reducing agent,” as used herein with respect to protein refolding, isdefined as any compound or material which maintains sulfhydryl groups inthe reduced state and reduces intra- or intermolecular disulfide bonds.Suitable reducing agents include, but are not limited to, dithiothreitol(DTT), 2-mercaptoethanol, dithioerythritol, cysteine, cysteamine(2-aminoethanethiol), and reduced glutathione. It is readily apparent tothose of ordinary skill in the art that a wide variety of reducingagents are suitable for use in the methods and compositions of thepresent invention.

“Oxidizing agent,” as used herein with respect to protein refolding, isdefined as any compound or material which is capable of removing anelectron from a compound being oxidized. Suitable oxidizing agentsinclude, but are not limited to, oxidized glutathione, cystine,cystamine, oxidized dithiothreitol, oxidized erythreitol, and oxygen. Itis readily apparent to those of ordinary skill in the art that a widevariety of oxidizing agents are suitable for use in the methods of thepresent invention.

“Denaturing agent” or “denaturant,” as used herein, is defined as anycompound or material which will cause a reversible unfolding of aprotein. The strength of a denaturing agent or denaturant will bedetermined both by the properties and the concentration of theparticular denaturing agent or denaturant. Suitable denaturing agents ordenaturants may be chaotropes, detergents, organic solvents, watermiscible solvents, phospholipids, or a combination of two or more suchagents. Suitable chaotropes include, but are not limited to, urea,guanidine, and sodium thiocyanate. Useful detergents may include, butare not limited to, strong detergents such as sodium dodecyl sulfate, orpolyoxyethylene ethers (e.g. Tween or Triton detergents), Sarkosyl, mildnon-ionic detergents (e.g., digitonin), mild cationic detergents such asN->2,3-(Dioleyoxy)-propyl-N,N,N-trimethylammonium, mild ionic detergents(e.g. sodium cholate or sodium deoxycholate) or zwitterionic detergentsincluding, but not limited to, sulfobetaines (Zwittergent),3-(3-chlolamidopropyl)dimethylammonio-1-propane sulfate (CHAPS), and3-(3-chlolamidopropyl)dimethylammonio-2-hydroxy-1-propane sulfonate(CHAPSO). Organic, water miscible solvents such as acetonitrile, loweralkanols (especially C₂-C₄ alkanols such as ethanol or isopropanol), orlower alkandiols (especially C₂-C₄ alkandiols such as ethylene-glycol)may be used as denaturants. Phospholipids useful in the presentinvention may be naturally occurring phospholipids such asphosphatidylethanolamine, phosphatidylcholine, phosphatidylserine, andphosphatidylinositol or synthetic phospholipid derivatives or variantssuch as dihexanoylphosphatidylcholine or diheptanoylphosphatidylcholine.

“Refolding,” as used herein describes any process, reaction or methodwhich transforms disulfide bond containing polypeptides from animproperly folded or unfolded state to a native or properly foldedconformation with respect to disulfide bonds.

“Cofolding,” as used herein, refers specifically to refolding processes,reactions, or methods which employ at least two polypeptides whichinteract with each other and result in the transformation of unfolded orimproperly folded polypeptides to native, properly folded polypeptides.

As used herein, “growth hormone” or “GH” shall include thosepolypeptides and proteins that have at least one biological activity ofa human growth hormone, as well as GH analogs, GH isoforms, GH mimetics,GH fragments, hybrid GH proteins, fusion proteins oligomers andmultimers, homologues, glycosylation pattern variants, and muteins,thereof, regardless of the biological activity of same, and furtherregardless of the method of synthesis or manufacture thereof including,but not limited to, recombinant (whether produced from cDNA, genomicDNA, synthetic DNA or other form of nucleic acid), synthetic,transgenic, and gene activated methods.

The term “hGH polypeptide” encompasses hGH polypeptides comprising oneor more amino acid substitutions, additions or deletions. Exemplarysubstitutions include, e.g., substitution of the lysine at position 41or the phenylalanine at position 176 of native hGH. In some cases, thesubstitution may be an isoleucine or arginine residue if thesubstitution is at position 41 or is a tyrosine residue if the positionis 176. Position F10 can be substituted with, e.g., A, H or I. PositionM14 may be substituted with, e.g., W, Q or G. Other exemplarysubstitutions include any substitutions or combinations thereof,including but not limited to:

R167N, D171S, E174S, F176Y, I179T;

R167E, D171S, E174S, F176Y;

F10A, M14W, H18D, H21N;

F10A, M14W, H18D, H21N, R167N, D171S, E174S, F176Y, I179T;

F10A, M14W, H18D, H21N, R167N, D171A, E174S, F176Y, I179T;

F10H, M14G, H18N, H21N;

F10A, M14W, H18D, H21N, R167N, D171A, T175T, I179T; or

F10I, M14Q, H18E, R167N, D171S, I179T. See, e.g., U.S. Pat. No.6,143,523, which is incorporated by reference herein.

Exemplary substitutions in a wide variety of amino acid positions innaturally-occurring hGH have been described, including substitutionsthat increase agonist activity, increase protease resistance, convertthe polypeptide into an antagonist, etc. and are encompassed by the term“hGH polypeptide.”

Agonist hGH sequences include, e.g., the naturally-occurring hGHsequence comprising the following modifications H18D, H21N, R167N,D171S, E174S, I179T. See, e.g., U.S. Pat. No. 5,849,535, which isincorporated by reference herein. Additional agonist hGH sequencesinclude

H18D, Q22A, F25A, D26A, Q29A, E65A, K168A, E174S;

H18A, Q22A, F25A, D26A, Q29A, E65A, K168A, E174S; or

H18D, Q22A, F25A, D26A, Q29A, E65A, K168A, E174A. See, e.g. U.S. Pat.No. 6,022,711, which is incorporated by reference herein. hGHpolypeptides comprising substitutions at H18A, Q22A, F25A, D26A, Q29A,E65A, K168A, E174A enhance affinity for the hGH receptor at site I. See,e.g. U.S. Pat. No. 5,854,026, which is incorporated by reference herein.hGH sequences with increased resistance to proteases include, but arenot limited to, hGH polypeptides comprising one or more amino acidsubstitutions within the C-D loop. In some embodiments, substitutionsinclude, but are not limited to, R134D, T135P, K140A, and anycombination thereof. See, e.g., Alam et al. (1998) J. Biotechnol.65:183-190.

Human Growth Hormone antagonists include, e.g., those with asubstitution at G120 (e.g., G120R, G120K, G120W, G120Y, G120F, or G120E)and sometimes further including the following substitutions: H18A, Q22A,F25A, D26A, Q29A, E65A, K168A, E174A. See, e.g. U.S. Pat. No. 6,004,931,which is incorporated by reference herein. In some embodiments, hGHantagonists comprise at least one substitution in the regions 106-108 or127-129 that cause GH to act as an antagonist. See, e.g., U.S. Pat. No.6,608,183, which is incorporated by reference herein. In someembodiments, the hGH antagonist comprises a non-naturally encoded aminoacid linked to a water soluble polymer that is present in the Site IIbinding region of the hGH molecule. In some embodiments, the hGHpolypeptide further comprises the following substitutions: H18D, H21N,R167N, K168A, D171S, K172R, E174S, I179T with a substitution at G120.(See, e.g, U.S. Pat. No. 5,849,535)

For the complete full-length naturally-occurring GH amino acid sequenceas well as the mature naturally-occurring GH amino acid sequence andnaturally occurring mutant, see SEQ ID NO: 1, SEQ ID NO: 2 and SEQ IDNO: 3, respectively, herein. In some embodiments, hGH polypeptides ofthe invention are substantially identical to SEQ ID NO: 1, or SEQ ID NO:2, or SEQ ID NO: 3 or any other sequence of a growth hormonepolypeptide. A number of naturally occurring mutants of hGH have beenidentified. These include hGH-V (Seeberg, DNA 1: 239 (1982); U.S. Pat.Nos. 4,446,235, 4,670,393, and 4,665,180, which are incorporated byreference herein) and a 20-kDa hGH containing a deletion of residues32-46 of hGH (SEQ ID NO: 3) (Kostyo et al., Biochem. Biophys. Acta 925:314 (1987); Lewis, U., et al., J. Biol. Chem., 253:2679-2687 (1978)).Placental growth hormone is described in Igout, A., et al., NucleicAcids Res. 17(10):3998 (1989)). In addition, numerous hGH variants,arising from post-transcriptional, post-translational, secretory,metabolic processing, and other physiological processes, have beenreported including proteolytically cleaved or 2 chain variants (Baumann,G., Endocrine Reviews 12: 424 (1991)). hGH dimers linked directly viaCys-Cys disulfide linkages are described in Lewis, U. J., et al., J.Biol. Chem. 252:3697-3702 (1977); Brostedt, P. and Roos, P., Prep.Biochem. 19:217-229 (1989)). Nucleic acid molecules encoding hGH mutantsand mutant hGH polypeptides are well known and include, but are notlimited to, those disclosed in U.S. Pat. Nos. 5,534,617; 5,580,723;5,688,666; 5,750,373; 5,834,250; 5,834,598; 5,849,535; 5,854,026;5,962,411; 5,955,346; 6,013,478; 6,022,711; 6,136,563; 6,143,523;6,428,954; 6,451,561; 6,780,613 and U.S. Patent Application Publication2003/0153003; which are incorporated by reference herein.

Commercial preparations of hGH are sold under the names: Humatrope™ (EliLilly & Co.), Nutropin™ (Genentech), Norditropin™ (Novo-Nordisk),Genotropin™ (Pfizer) and Saizen/Serostim™ (Serono).

The term “hGH polypeptide” also includes the pharmaceutically acceptablesalts and prodrugs, and prodrugs of the salts, polymorphs, hydrates,solvates, biologically-active fragments, biologically active variantsand stereoisomers of the naturally-occurring hGH as well as agonist,mimetic, and antagonist variants of the naturally-occurring hGH andpolypeptide fusions thereof. Fusions comprising additional amino acidsat the amino terminus, carboxyl terminus, or both, are encompassed bythe term “hGH polypeptide.” Exemplary fusions include, but are notlimited to, e.g., methionyl growth hormone in which a methionine islinked to the N-terminus of hGH resulting from the recombinantexpression, fusions for the purpose of purification (including, but notlimited to, to poly-histidine or affinity epitopes), fusions with serumalbumin binding peptides and fusions with serum proteins such as serumalbumin.

Various references disclose modification of polypeptides by polymerconjugation or glycosylation. The term “hGH polypeptide” includespolypeptides conjugated to a polymer such as PEG and may be comprised ofone or more additional derivatizations of cysteine, lysine, or otherresidues. In addition, the hGH polypeptide may comprise a linker orpolymer, wherein the amino acid to which the linker or polymer isconjugated may be a non-natural amino acid according to the presentinvention, or may be conjugated to a naturally encoded amino acidutilizing techniques known in the art such as coupling to lysine orcysteine.

Polymer conjugation of hGH polypeptides has been reported. See, e.g.U.S. Pat. Nos. 5,849,535, 6,136,563 and 6,608,183, which areincorporated by reference herein. U.S. Pat. No. 4,904,584 disclosesPEGylated lysine depleted polypeptides, wherein at least one lysineresidue has been deleted or replaced with any other amino acid residue.WO 99/67291 discloses a process for conjugating a protein with PEG,wherein at least one amino acid residue on the protein is deleted andthe protein is contacted with PEG under conditions sufficient to achieveconjugation to the protein. WO 99/03887 discloses PEGylated variants ofpolypeptides belonging to the growth hormone superfamily, wherein acysteine residue has been substituted with a non-essential amino acidresidue located in a specified region of the polypeptide. WO 00/26354discloses a method of producing a glycosylated polypeptide variant withreduced allergenicity, which as compared to a corresponding parentpolypeptide comprises at least one additional glycosylation site.

The term “hGH polypeptide” also includes N-linked or O-linkedglycosylated forms of the polypeptide. Variants containing singlenucleotide changes are also considered as biologically active variantsof hGH polypeptide. In addition, splice variants are also included. Theterm “hGH polypeptide” also includes hGH polypeptide heterodimers,homodimers, heteromultimers, or homomultimers of any one or more hGHpolypeptides or any other polypeptide, protein, carbohydrate, polymer,small molecule, ligand, or other active molecule of any type, linked bychemical means or expressed as a fusion protein, as well as polypeptideanalogues containing, for example, specific deletions or othermodifications yet maintain biological activity.

All references to amino acid positions in hGH described herein are basedon the position in SEQ ID NO: 2, unless otherwise specified (i.e., whenit is stated that the comparison is based on SEQ ID NO: 1, 3, or otherhGH sequence). Those of skill in the art will appreciate that amino acidpositions corresponding to positions in SEQ ID NO: 1, 2, 3, or any otherGH sequence can be readily identified in any other hGH molecule such ashGH fusions, variants, fragments, etc. For example, sequence alignmentprograms such as BLAST can be used to align and identify a particularposition in a protein that corresponds with a position in SEQ ID NO: 1,2, 3, or other GH sequence. Substitutions, deletions or additions ofamino acids described herein in reference to SEQ ID NO: 1, 2, 3, orother GH sequence are intended to also refer to substitutions, deletionsor additions in corresponding positions in hGH fusions, variants,fragments, etc. described herein or known in the art and are expresslyencompassed by the present invention.

The term “hGH polypeptide” encompasses hGH polypeptides comprising oneor more amino acid substitutions, additions or deletions. hGHpolypeptides of the present invention may be comprised of modificationswith one or more natural amino acids in conjunction with one or morenon-natural amino acid modification. Exemplary substitutions in a widevariety of amino acid positions in naturally-occurring hGH polypeptideshave been described, including but not limited to substitutions thatmodulate one or more of the biological activities of the hGHpolypeptide, such as but not limited to, increase agonist activity,increase solubility of the polypeptide, convert the polypeptide into anantagonist, etc. and are encompassed by the term “hGH polypeptide.”

Human GH antagonists include, but are not limited to, those withsubstitutions at: 1, 2, 3, 4, 5, 8, 9, 11, 12, 15, 16, 19, 22, 103, 109,112, 113, 115, 116, 119, 120, 123, and 127 or an addition at position 1(i.e., at the N-terminus), or any combination thereof (SEQ ID NO:2, orthe corresponding amino acid in SEQ ID NO: 1, 3, or any other GHsequence). In some embodiments, hGH antagonists comprise at least onesubstitution in the regions 1-5 (N-terminus), 6-33 (A helix), 34-74(region between A helix and B helix, the A-B loop), 75-96 (B helix),97-105 (region between B helix and C helix, the B-C loop), 106-129 (Chelix), 130-153 (region between C helix and D helix, the C-D loop),154-183 (D helix), 184-191 (C-terminus) that cause GH to act as anantagonist. In other embodiments, the exemplary sites of incorporationof a non-naturally encoded amino acid include residues within the aminoterminal region of helix A and a portion of helix C. In anotherembodiment, substitution of G120 with a non-naturally encoded amino acidsuch as p-azido-L-phenyalanine or O-propargyl-L-tyrosine. In otherembodiments, the above-listed substitutions are combined with additionalsubstitutions that cause the hGH polypeptide to be an hGH antagonist.For instance, a non-naturally encoded amino acid is substituted at oneof the positions identified herein and a simultaneous substitution isintroduced at G120 (e.g., G120R, G120K, G120W, G120Y, G120F, or G120E).In some embodiments, the hGH antagonist comprises a non-naturallyencoded amino acid linked to a water soluble polymer that is present ina receptor binding region of the hGH molecule.

In some embodiments, the hGH polypeptides further comprise an addition,substitution or deletion that modulates biological activity of the hGHpolypeptide. For example, the additions, substitutions or deletions maymodulate affinity for the hGH polypeptide receptor, modulate (includingbut not limited to, increases or decreases) receptor dimerization,stabilize receptor dimers, modulate circulating half-life, modulatetherapeutic half-life, modulate stability of the polypeptide, modulatedose, modulate release or bio-availability, facilitate purification, orimprove or alter a particular route of administration. Similarly, hGHpolypeptides may comprise protease cleavage sequences, reactive groups,antibody-binding domains (including but not limited to, FLAG orpoly-His) or other affinity based sequences (including but not limitedto, FLAG, poly-His, GST, etc.) or linked molecules (including but notlimited to, biotin) that improve detection (including but not limitedto, GFP), purification or other traits of the polypeptide.

The term “hGH polypeptide” also encompasses homodimers, heterodimers,homomultimers, and heteromultimers that are linked, including but notlimited to those linked directly via non-naturally encoded amino acidside chains, either to the same or different non-naturally encoded aminoacid side chains, to naturally-encoded amino acid side chains, orindirectly via a linker. Exemplary linkers including but are not limitedto, water soluble polymers such as poly(ethylene glycol) or polydextranor a polypeptide.

A “non-naturally encoded amino acid” refers to an amino acid that is notone of the 20 common amino acids or pyrolysine or selenocysteine. Otherterms that may be used synonymously with the term “non-naturally encodedamino acid” are “non-natural amino acid,” “unnatural amino acid,”“non-naturally-occurring amino acid,” and variously hyphenated andnon-hyphenated versions thereof. The term “non-naturally encoded aminoacid” also includes, but is not limited to, amino acids that occur bymodification (e.g. post-translational modifications) of a naturallyencoded amino acid (including but not limited to, the 20 common aminoacids or pyrolysine and selenocysteine) but are not themselves naturallyincorporated into a growing polypeptide chain by the translationcomplex. Examples of such non-naturally-occurring amino acids include,but are not limited to, N-acetylglucosaminyl-L-serine,N-acetylglucosaminyl-L-threonine, and O-phosphotyrosine.

An “amino terminus modification group” refers to any molecule that canbe attached to the amino terminus of a polypeptide. Similarly, a“carboxy terminus modification group” refers to any molecule that can beattached to the carboxy terminus of a polypeptide. Terminus modificationgroups include, but are not limited to, various water soluble polymers,peptides or proteins such as serum albumin, or other moieties thatincrease serum half-life of peptides.

The terms “functional group”, “active moiety”, “activating group”,“leaving group”, “reactive site”, “chemically reactive group” and“chemically reactive moiety” are used in the art and herein to refer todistinct, definable portions or units of a molecule. The terms aresomewhat synonymous in the chemical arts and are used herein to indicatethe portions of molecules that perform some function or activity and arereactive with other molecules.

The term “linkage” or “linker” is used herein to refer to groups orbonds that normally are formed as the result of a chemical reaction andtypically are covalent linkages. Hydrolytically stable linkages meansthat the linkages are substantially stable in water and do not reactwith water at useful pH values, including but not limited to, underphysiological conditions for an extended period of time, perhaps evenindefinitely. Hydrolytically unstable or degradable linkages mean thatthe linkages are degradable in water or in aqueous solutions, includingfor example, blood. Enzymatically unstable or degradable linkages meanthat the linkage can be degraded by one or more enzymes. As understoodin the art, PEG and related polymers may include degradable linkages inthe polymer backbone or in the linker group between the polymer backboneand one or more of the terminal functional groups of the polymermolecule. For example, ester linkages formed by the reaction of PEGcarboxylic acids or activated PEG carboxylic acids with alcohol groupson a biologically active agent generally hydrolyze under physiologicalconditions to release the agent. Other hydrolytically degradablelinkages include, but are not limited to, carbonate linkages; iminelinkages resulted from reaction of an amine and an aldehyde; phosphateester linkages formed by reacting an alcohol with a phosphate group;hydrazone linkages which are reaction product of a hydrazide and analdehyde; acetal linkages that are the reaction product of an aldehydeand an alcohol; orthoester linkages that are the reaction product of aformate and an alcohol; peptide linkages formed by an amine group,including but not limited to, at an end of a polymer such as PEG, and acarboxyl group of a peptide; and oligonucleotide linkages formed by aphosphoramidite group, including but not limited to, at the end of apolymer, and a 5′ hydroxyl group of an oligonucleotide.

The term “biologically active molecule”, “biologically active moiety” or“biologically active agent” when used herein means any substance whichcan affect any physical or biochemical properties of a biologicalorganism, including but not limited to, viruses, bacteria, fungi,plants, animals, and humans. In particular, as used herein, biologicallyactive molecules include, but are not limited to, any substance intendedfor diagnosis, cure, mitigation, treatment, or prevention of disease inhumans or other animals, or to otherwise enhance physical or mentalwell-being of humans or animals. Examples of biologically activemolecules include, but are not limited to, peptides, proteins, enzymes,small molecule drugs, dyes, lipids, nucleosides, oligonucleotides,cells, viruses, liposomes, microparticles and micelles. Classes ofbiologically active agents that are suitable for use with the inventioninclude, but are not limited to, antibiotics, fungicides, anti-viralagents, anti-inflammatory agents, anti-tumor agents, cardiovascularagents, anti-anxiety agents, hormones, growth factors, steroidal agents,and the like.

A “bifunctional polymer” refers to a polymer comprising two discretefunctional groups that are capable of reacting specifically with othermoieties (including but not limited to, amino acid side groups) to formcovalent or non-covalent linkages. A bifunctional linker having onefunctional group reactive with a group on a particular biologicallyactive component, and another group reactive with a group on a secondbiological component, may be used to form a conjugate that includes thefirst biologically active component, the bifunctional linker and thesecond biologically active component. Many procedures and linkermolecules for attachment of various compounds to peptides are known.See, e.g., European Patent Application No. 188,256; U.S. Pat. Nos.4,671,958, 4,659,839, 4,414,148, 4,699,784; 4,680,338; 4,569,789; and4,589,071 which are incorporated by reference herein. A“multi-functional polymer” refers to a polymer comprising two or morediscrete functional groups that are capable of reacting specificallywith other moieties (including but not limited to, amino acid sidegroups) to form covalent or non-covalent linkages.

Where substituent groups are specified by their conventional chemicalformulas, written from left to right, they equally encompass thechemically identical substituents that would result from writing thestructure from right to left, for example, the structure —CH₂O— isequivalent to the structure —OCH₂—.

The term “substituents” includes but is not limited to “non-interferingsubstituents”. “Non-interfering substituents” are those groups thatyield stable compounds. Suitable non-interfering substituents orradicals include, but are not limited to, halo, C₁-C₁₀ alkyl, C₂-C₁₀alkenyl, C₂-C₁₀ alkynyl, C₁-C₁₀ alkoxy, C₁-C₁₂ aralkyl, C₁-C₁₂ alkaryl,C₃-C₁₂ cycloalkyl, C₃-C₁₂ cycloalkenyl, phenyl, substituted phenyl,toluoyl, xylenyl, biphenyl, C₂-C₁₂ alkoxyalkyl, C₂-C₁₂ alkoxyaryl,C₇-C₁₂ aryloxyalkyl, C₇-C₁₂ oxyaryl, C₁-C₆ alkylsulfinyl, C₁-C₁₀alkylsulfonyl, —(CH₂)_(m)—O—(C₁-C₁₀ alkyl) wherein m is from 1 to 8,aryl, substituted aryl, substituted alkoxy, fluoroalkyl, heterocyclicradical, substituted heterocyclic radical, nitroalkyl, —NO₂, —CN,—NRC(O)—(C₁-C₁₀ alkyl), —C(O)—(C₁-C₁₀ alkyl), C₂-C₁₀ alkyl thioalkyl,—C(O)O—(C₁-C₁₀ alkyl), —OH, —SO₂, ═S, —COOH, —NR₂, carbonyl,—C(O)—(C₁-C₁₀ alkyl)-CF3, —C(O)—CF3, —C(O)NR2, —(C₁-C₁₀ aryl)-S—(C₆-C₁₀aryl), —C(O)—(C₁-C₁₀ aryl), —(CH₂)_(m)—O—(—(CH₂)_(m)—O—(C₁-C₁₀ alkyl)wherein each m is from 1 to 8, —C(O)NR₂, —C(S)NR₂, —SO₂NR₂, —NRC(O)NR₂,—NRC(S)NR₂, salts thereof, and the like. Each R as used herein is H,alkyl or substituted alkyl, aryl or substituted aryl, aralkyl, oralkaryl.

The term “halogen” includes fluorine, chlorine, iodine, and bromine.

The term “alkyl,” by itself or as part of another substituent, means,unless otherwise stated, a straight or branched chain, or cyclichydrocarbon radical, or combination thereof, which may be fullysaturated, mono- or polyunsaturated and can include di- and multivalentradicals, having the number of carbon atoms designated (i.e. C₁-C₁₀means one to ten carbons). Examples of saturated hydrocarbon radicalsinclude, but are not limited to, groups such as methyl, ethyl, n-propyl,isopropyl, n-butyl, t-butyl, isobutyl, sec-butyl, cyclohexyl,(cyclohexyl)methyl, cyclopropylmethyl, homologs and isomers of, forexample, n-pentyl, n-hexyl, n-heptyl, n-octyl, and the like. Anunsaturated alkyl group is one having one or more double bonds or triplebonds. Examples of unsaturated alkyl groups include, but are not limitedto, vinyl, 2-propenyl, crotyl, 2-isopentenyl, 2-(butadienyl),2,4-pentadienyl, 3-(1,4-pentadienyl), ethynyl, 1- and 3-propynyl,3-butynyl, and the higher homologs and isomers. The term “alkyl,” unlessotherwise noted, is also meant to include those derivatives of alkyldefined in more detail below, such as “heteroalkyl.” Alkyl groups whichare limited to hydrocarbon groups are termed “homoalkyl”.

The term “alkylene” by itself or as part of another substituent means adivalent radical derived from an alkane, as exemplified, but notlimited, by the structures —CH₂CH₂— and —CH₂CH₂CH₂CH₂—, and furtherincludes those groups described below as “heteroalkylene.” Typically, analkyl (or alkylene) group will have from 1 to 24 carbon atoms, withthose groups having 10 or fewer carbon atoms being preferred in thepresent invention. A “lower alkyl” or “lower alkylene” is a shorterchain alkyl or alkylene group, generally having eight or fewer carbonatoms.

The terms “alkoxy,” “alkylamino” and “alkylthio” (or thioalkoxy) areused in their conventional sense, and refer to those alkyl groupsattached to the remainder of the molecule via an oxygen atom, an aminogroup, or a sulfur atom, respectively.

The term “heteroalkyl,” by itself or in combination with another term,means, unless otherwise stated, a stable straight or branched chain, orcyclic hydrocarbon radical, or combinations thereof, consisting of thestated number of carbon atoms and at least one heteroatom selected fromthe group consisting of O, N, Si and S, and wherein the nitrogen andsulfur atoms may optionally be oxidized and the nitrogen heteroatom mayoptionally be quaternized. The heteroatom(s) O, N and S and Si may beplaced at any interior position of the heteroalkyl group or at theposition at which the alkyl group is attached to the remainder of themolecule. Examples include, but are not limited to, —CH₂—CH₂—O—CH₃,—CH₂—CH₂—NH—CH₃, —CH₂—CH₂—N(CH₃)—CH₃, —CH₂—S—CH₂—CH₃, —CH₂—CH₂,—S(O)—CH₃, —CH₂—CH₂—S(O)₂—CH₃, —CH═CH—O—CH₃, —Si(CH₃)₃, —CH₂—CH═N—OCH₃,and —CH═CH—N(CH₃)—CH₃. Up to two heteroatoms may be consecutive, suchas, for example, —CH₂—NH—OCH₃ and —CH₂—O—Si(CH₃)₃. Similarly, the term“heteroalkylene” by itself or as part of another substituent means adivalent radical derived from heteroalkyl, as exemplified, but notlimited by, —CH₂—CH₂—S—CH₂—CH₂— and —CH₂—S—CH₂—CH₂—NH—CH₂—. Forheteroalkylene groups, the same or different heteroatoms can also occupyeither or both of the chain termini (including but not limited to,alkyleneoxy, alkylenedioxy, alkyleneamino, alkylenediamino,aminooxyalkylene, and the like). Still further, for alkylene andheteroalkylene linking groups, no orientation of the linking group isimplied by the direction in which the formula of the linking group iswritten. For example, the formula —C(O)₂R′— represents both —C(O)₂R′—and —R′C(O)₂—.

The terms “cycloalkyl” and “heterocycloalkyl”, by themselves or incombination with other terms, represent, unless otherwise stated, cyclicversions of “alkyl” and “heteroalkyl”, respectively. Thus, a cycloalkylor heterocycloalkyl include saturated and unsaturated ring linkages.Additionally, for heterocycloalkyl, a heteroatom can occupy the positionat which the heterocycle is attached to the remainder of the molecule.Examples of cycloalkyl include, but are not limited to, cyclopentyl,cyclohexyl, 1-cyclohexenyl, 3-cyclohexenyl, cycloheptyl, and the like.Examples of heterocycloalkyl include, but are not limited to,1-(1,2,5,6-tetrahydropyridyl), 1-piperidinyl, 2-piperidinyl,3-piperidinyl, 4-morpholinyl, 3-morpholinyl, tetrahydrofuran-2-yl,tetrahydrofuran-3-yl, tetrahydrothien-2-yl, tetrahydrothien-3-yl,1-piperazinyl, 2-piperazinyl, and the like. Additionally, the termencompasses bicyclic and tricyclic ring structures. Similarly, the term“heterocycloalkylene” by itself or as part of another substituent meansa divalent radical derived from heterocycloalkyl, and the term“cycloalkylene” by itself or as part of another substituent means adivalent radical derived from cycloalkyl.

As used herein, the term “water soluble polymer” refers to any polymerthat is soluble in aqueous solvents. Linkage of water soluble polymersto hGH polypeptides can result in changes including, but not limited to,increased or modulated serum half-life, or increased or modulatedtherapeutic half-life relative to the unmodified form, modulatedimmunogenicity, modulated physical association characteristics such asaggregation and multimer formation, altered receptor binding and alteredreceptor dimerization or multimerization. The water soluble polymer mayor may not have its own biological activity. Suitable polymers include,but are not limited to, polyethylene glycol, polyethylene glycolpropionaldehyde, mono C1-C10 alkoxy or aryloxy derivatives thereof(described in U.S. Pat. No. 5,252,714 which is incorporated by referenceherein), monomethoxy-polyethylene glycol, polyvinyl pyrrolidone,polyvinyl alcohol, polyamino acids, divinylether maleic anhydride,N-(2-Hydroxypropyl)-methacrylamide, dextran, dextran derivativesincluding dextran sulfate, polypropylene glycol, polypropyleneoxide/ethylene oxide copolymer, polyoxyethylated polyol, heparin,heparin fragments, polysaccharides, oligosaccharides, glycans, celluloseand cellulose derivatives, including but not limited to methylcelluloseand carboxymethyl cellulose, starch and starch derivatives,polypeptides, polyalkylene glycol and derivatives thereof, copolymers ofpolyalkylene glycols and derivatives thereof, polyvinyl ethyl ethers,and alpha-beta-poly[(2-hydroxyethyl)-DL-aspartamide, and the like, ormixtures thereof. Examples of such water soluble polymers include, butare not limited to, polyethylene glycol and serum albumin.

As used herein, the term “polyalkylene glycol” or “poly(alkene glycol)”refers to polyethylene glycol (poly(ethylene glycol)), polypropyleneglycol, polybutylene glycol, and derivatives thereof. The term“polyalkylene glycol” encompasses both linear and branched polymers andaverage molecular weights of between 0.1 kDa and 100 kDa. Otherexemplary embodiments are listed, for example, in commercial suppliercatalogs, such as Shearwater Corporation's catalog “Polyethylene Glycoland Derivatives for Biomedical Applications” (2001).

The term “aryl” means, unless otherwise stated, a polyunsaturated,aromatic, hydrocarbon substituent which can be a single ring or multiplerings (preferably from 1 to 3 rings) which are fused together or linkedcovalently. The term “heteroaryl” refers to aryl groups (or rings) thatcontain from one to four heteroatoms selected from N, O, and S, whereinthe nitrogen and sulfur atoms are optionally oxidized, and the nitrogenatom(s) are optionally quaternized. A heteroaryl group can be attachedto the remainder of the molecule through a heteroatom. Non-limitingexamples of aryl and heteroaryl groups include phenyl, 1-naphthyl,2-naphthyl, 4-biphenyl, 1-pyrrolyl, 2-pyrrolyl, 3-pyrrolyl, 3-pyrazolyl,2-imidazolyl, 4-imidazolyl, pyrazinyl, 2-oxazolyl, 4-oxazolyl,2-phenyl-4-oxazolyl, 5-oxazolyl, 3-isoxazolyl, 4-isoxazolyl,5-isoxazolyl, 2-thiazolyl, 4-thiazolyl, 5-thiazolyl, 2-furyl, 3-furyl,2-thienyl, 3-thienyl, 2-pyridyl, 3-pyridyl, 4-pyridyl, 2-pyrimidyl,4-pyrimidyl, 5-benzothiazolyl, purinyl, 2-benzimidazolyl, 5-indolyl,1-isoquinolyl, 5-isoquinolyl, 2-quinoxalinyl, 5-quinoxalinyl,3-quinolyl, and 6-quinolyl. Substituents for each of the above notedaryl and heteroaryl ring systems are selected from the group ofacceptable substituents described below.

For brevity, the term “aryl” when used in combination with other terms(including but not limited to, aryloxy, arylthioxy, arylalkyl) includesboth aryl and heteroaryl rings as defined above. Thus, the term“arylalkyl” is meant to include those radicals in which an aryl group isattached to an alkyl group (including but not limited to, benzyl,phenethyl, pyridylmethyl and the like) including those alkyl groups inwhich a carbon atom (including but not limited to, a methylene group)has been replaced by, for example, an oxygen atom (including but notlimited to, phenoxymethyl, 2-pyridyloxymethyl, 3-(1-naphthyloxy)propyl,and the like).

Each of the above terms (including but not limited to, “alkyl,”“heteroalkyl,” “aryl” and “heteroaryl”) are meant to include bothsubstituted and unsubstituted forms of the indicated radical. Exemplarysubstituents for each type of radical are provided below.

Substituents for the alkyl and heteroalkyl radicals (including thosegroups often referred to as alkylene, alkenyl, heteroalkylene,heteroalkenyl, alkynyl, cycloalkyl, heterocycloalkyl, cycloalkenyl, andheterocycloalkenyl) can be one or more of a variety of groups selectedfrom, but not limited to: —OR′, ═O, ═NR′, ═N—OR′, —NR′R″, —SR′,-halogen, —SiR′R″R′″, —OC(O)R′, —C(O)R′, —CO₂R′, —CONR′R″, —OC(O)NR′R″,—NR″C(O)R′, —NR′—C(O)NR″R′″, —NR″C(O)₂R′, —NR—C(NR′R″R′″)═NR″″,—NR—C(NR′R″)═NR′″, —S(O)R′, —S(O)₂R′, —S(O)₂NR′R″, —NRSO₂R′, —CN and—NO₂ in a number ranging from zero to (2m′+1), where m′ is the totalnumber of carbon atoms in such a radical. R′, R″, R′″ and R″″ eachindependently refer to hydrogen, substituted or unsubstitutedheteroalkyl, substituted or unsubstituted aryl, including but notlimited to, aryl substituted with 1-3 halogens, substituted orunsubstituted alkyl, alkoxy or thioalkoxy groups, or arylalkyl groups.When a compound of the invention includes more than one R group, forexample, each of the R groups is independently selected as are each R′,R″, R′″ and R″″ groups when more than one of these groups is present.When R′ and R″ are attached to the same nitrogen atom, they can becombined with the nitrogen atom to form a 5-, 6-, or 7-membered ring.For example, —NR′R″ is meant to include, but not be limited to,1-pyrrolidinyl and 4-morpholinyl. From the above discussion ofsubstituents, one of skill in the art will understand that the term“alkyl” is meant to include groups including carbon atoms bound togroups other than hydrogen groups, such as haloalkyl (including but notlimited to, —CF₃ and —CH₂CF₃) and acyl (including but not limited to,—C(O)CH₃, —C(O)CF₃, —C(O)CH₂OCH₃, and the like).

Similar to the substituents described for the alkyl radical,substituents for the aryl and heteroaryl groups are varied and areselected from, but are not limited to: halogen, —OR′, ═O, ═NR′, ═N—OR′,—NR′R″, —SR′, -halogen, —SiR′R″R′″, —OC(O)R′, —C(O)R′, —CO₂R′, CONR′R″,—OC(O)NR′R″, —NR″C(O)R′, —NR′—C(O)NR″R′″, —NR″C(O)₂R′,—NR—C(NR′R″R′″)═NR″″, —NR—C(NR′R″)═NR′″, —S(O)R′, —S(O)₂R′, —S(O)₂NR′R″,—NRSO₂R′, —CN and —NO₂, —R′, —N₃, —CH(Ph)₂, fluoro(C₁-C₄)alkoxy, andfluoro(C₁-C₄)alkyl, in a number ranging from zero to the total number ofopen valences on the aromatic ring system; and where R′, R″, R′″ and R″″are independently selected from hydrogen, alkyl, heteroalkyl, aryl andheteroaryl. When a compound of the invention includes more than one Rgroup, for example, each of the R groups is independently selected asare each R′, R″, R′″ and R″″ groups when more than one of these groupsis present.

As used herein, the term “modulated serum half-life” means the positiveor negative change in circulating half-life of a modified biologicallyactive molecule relative to its non-modified form. Serum half-life ismeasured by taking blood samples at various time points afteradministration of the biologically active molecule, and determining theconcentration of that molecule in each sample. Correlation of the serumconcentration with time allows calculation of the serum half-life.Increased serum half-life desirably has at least about two-fold, but asmaller increase may be useful, for example where it enables asatisfactory dosing regimen or avoids a toxic effect. In someembodiments, the increase is at least about three-fold, at least aboutfive-fold, or at least about ten-fold.

The term “modulated therapeutic half-life” as used herein means thepositive or negative change in the half-life of the therapeuticallyeffective amount of a modified biologically active molecule, relative toits non-modified form. Therapeutic half-life is measured by measuringpharmacokinetic and/or pharmacodynamic properties of the molecule atvarious time points after administration. Increased therapeutichalf-life desirably enables a particular beneficial dosing regimen, aparticular beneficial total dose, or avoids an undesired effect. In someembodiments, the increased therapeutic half-life results from increasedpotency, increased or decreased binding of the modified molecule to itstarget, or an increase or decrease in another parameter or mechanism ofaction of the non-modified molecule.

The term “isolated,” when applied to a nucleic acid or protein, denotesthat the nucleic acid or protein is substantially free of other cellularcomponents with which it is associated in the natural state. It can bein a homogeneous state. Isolated substances can be in either a dry orsemi-dry state, or in solution, including but not limited to, an aqueoussolution. Purity and homogeneity are typically determined usinganalytical chemistry techniques such as polyacrylamide gelelectrophoresis or high performance liquid chromatography. A proteinwhich is the predominant species present in a preparation issubstantially purified. In particular, an isolated gene is separatedfrom open reading frames which flank the gene and encode a protein otherthan the gene of interest. The term “purified” denotes that a nucleicacid or protein gives rise to substantially one band in anelectrophoretic gel. Particularly, it means that the nucleic acid orprotein is at least 85% pure, at least 90% pure, at least 95% pure, atleast 99% or greater pure.

The term “nucleic acid” refers to deoxyribonucleotides,deoxyribonucleosides, ribonucleosides, or ribonucleotides and polymersthereof in either single- or double-stranded form. Unless specificallylimited, the term encompasses nucleic acids containing known analoguesof natural nucleotides which have similar binding properties as thereference nucleic acid and are metabolized in a manner similar tonaturally occurring nucleotides. Unless specifically limited otherwise,the term also refers to oligonucleotide analogs including PNA(peptidonucleic acid), analogs of DNA used in antisense technology(phosphorothioates, phosphoroamidates, and the like). Unless otherwiseindicated, a particular nucleic acid sequence also implicitlyencompasses conservatively modified variants thereof (including but notlimited to, degenerate codon substitutions) and complementary sequencesas well as the sequence explicitly indicated. Specifically, degeneratecodon substitutions may be achieved by generating sequences in which thethird position of one or more selected (or all) codons is substitutedwith mixed-base and/or deoxyinosine residues (Batzer et al., NucleicAcid Res. 19:5081 (1991); Ohtsuka et al., J. Biol. Chem. 260:2605-2608(1985); and Cassol et al. (1992); Rossolini et al., Mol. Cell. Probes8:91-98 (1994)).

The terms “polypeptide,” “peptide” and “protein” are usedinterchangeably herein to refer to a polymer of amino acid residues.That is, a description directed to a polypeptide applies equally to adescription of a peptide and a description of a protein, and vice versa.The terms apply to naturally occurring amino acid polymers as well asamino acid polymers in which one or more amino acid residues is anon-naturally encoded amino acid. As used herein, the terms encompassamino acid chains of any length, including full length proteins (i.e.,antigens), wherein the amino acid residues are linked by covalentpeptide bonds.

The term “amino acid” refers to naturally occurring and non-naturallyoccurring amino acids, as well as amino acid analogs and amino acidmimetics that function in a manner similar to the naturally occurringamino acids. Naturally encoded amino acids are the 20 common amino acids(alanine, arginine, asparagine, aspartic acid, cysteine, glutamine,glutamic acid, glycine, histidine, isoleucine, leucine, lysine,methionine, phenylalanine, proline, serine, threonine, tryptophan,tyrosine, and valine) and pyrolysine and selenocysteine. Amino acidanalogs refers to compounds that have the same basic chemical structureas a naturally occurring amino acid, i.e., an a carbon that is bound toa hydrogen, a carboxyl group, an amino group, and an R group, such as,homoserine, norleucine, methionine sulfoxide, methionine methylsulfonium. Such analogs have modified R groups (such as, norleucine) ormodified peptide backbones, but retain the same basic chemical structureas a naturally occurring amino acid.

Amino acids may be referred to herein by either their commonly knownthree letter symbols or by the one-letter symbols recommended by theIUPAC-IUB Biochemical Nomenclature Commission. Nucleotides, likewise,may be referred to by their commonly accepted single-letter codes.

“Conservatively modified variants” applies to both amino acid andnucleic acid sequences. With respect to particular nucleic acidsequences, “conservatively modified variants” refers to those nucleicacids which encode identical or essentially identical amino acidsequences, or where the nucleic acid does not encode an amino acidsequence, to essentially identical sequences. Because of the degeneracyof the genetic code, a large number of functionally identical nucleicacids encode any given protein. For instance, the codons GCA, GCC, GCGand GCU all encode the amino acid alanine. Thus, at every position wherean alanine is specified by a codon, the codon can be altered to any ofthe corresponding codons described without altering the encodedpolypeptide. Such nucleic acid variations are “silent variations,” whichare one species of conservatively modified variations. Every nucleicacid sequence herein which encodes a polypeptide also describes everypossible silent variation of the nucleic acid. One of skill willrecognize that each codon in a nucleic acid (except AUG, which isordinarily the only codon for methionine, and TGG, which is ordinarilythe only codon for tryptophan) can be modified to yield a functionallyidentical molecule. Accordingly, each silent variation of a nucleic acidwhich encodes a polypeptide is implicit in each described sequence.

As to amino acid sequences, one of skill will recognize that individualsubstitutions, deletions or additions to a nucleic acid, peptide,polypeptide, or protein sequence which alters, adds or deletes a singleamino acid or a small percentage of amino acids in the encoded sequenceis a “conservatively modified variant” where the alteration results inthe substitution of an amino acid with a chemically similar amino acid.Conservative substitution tables providing functionally similar aminoacids are well known in the art. Such conservatively modified variantsare in addition to and do not exclude polymorphic variants, interspecieshomologs, and alleles of the invention.

The following eight groups each contain amino acids that areconservative substitutions for one another:

1) Alanine (A), Glycine (G);

2) Aspartic acid (D), Glutamic acid (E);

3) Asparagine (N), Glutamine (Q);

4) Arginine (R), Lysine (K);

5) Isoleucine (I), Leucine (L), Methionine (M), Valine (V);

6) Phenylalanine (F), Tyrosine (Y), Tryptophan (W);

7) Serine (S), Threonine (T); and

8) Cysteine (C), Methionine (M)

(see, e.g., Creighton, Proteins: Structures and Molecular Properties (WH Freeman & Co.; 2nd edition (December 1993)

The terms “identical” or percent “identity,” in the context of two ormore nucleic acids or polypeptide sequences, refer to two or moresequences or subsequences that are the same. Sequences are“substantially identical” if they have a percentage of amino acidresidues or nucleotides that are the same (i.e., about 60% identity,optionally about 65%, about 70%, about 75%, about 80%, about 85%, about90%, or about 95% identity over a specified region), when compared andaligned for maximum correspondence over a comparison window, ordesignated region as measured using one of the following sequencecomparison algorithms or by manual alignment and visual inspection. Thisdefinition also refers to the complement of a test sequence. Theidentity can exist over a region that is at least about 50 amino acidsor nucleotides in length, or over a region that is 75-100 amino acids ornucleotides in length, or, where not specified, across the entiresequence or a polynucleotide or polypeptide.

For sequence comparison, typically one sequence acts as a referencesequence, to which test sequences are compared. When using a sequencecomparison algorithm, test and reference sequences are entered into acomputer, subsequence coordinates are designated, if necessary, andsequence algorithm program parameters are designated. Default programparameters can be used, or alternative parameters can be designated. Thesequence comparison algorithm then calculates the percent sequenceidentities for the test sequences relative to the reference sequence,based on the program parameters.

A “comparison window”, as used herein, includes reference to a segmentof any one of the number of contiguous positions selected from the groupconsisting of from 20 to 600, usually about 50 to about 200, moreusually about 100 to about 150 in which a sequence may be compared to areference sequence of the same number of contiguous positions after thetwo sequences are optimally aligned. Methods of alignment of sequencesfor comparison are well-known in the art. Optimal alignment of sequencesfor comparison can be conducted, including but not limited to, by thelocal homology algorithm of Smith and Waterman (1970) Adv. Appl. Math.2:482c, by the homology alignment algorithm of Needleman and Wunsch(1970) J. Mol. Biol. 48:443, by the search for similarity method ofPearson and Lipman (1988) Proc. Nat'l. Acad. Sci. USA 85:2444, bycomputerized implementations of these algorithms (GAP, BESTFIT, FASTA,and TFASTA in the Wisconsin Genetics Software Package, Genetics ComputerGroup, 575 Science Dr., Madison, Wis.), or by manual alignment andvisual inspection (see, e.g., Ausubel et al., Current Protocols inMolecular Biology (1995 supplement)).

One example of an algorithm that is suitable for determining percentsequence identity and sequence similarity are the BLAST and BLAST 2.0algorithms, which are described in Altschul et al. (1977) Nuc. AcidsRes. 25:3389-3402, and Altschul et al. (1990) J. Mol. Biol. 215:403-410,respectively. Software for performing BLAST analyses is publiclyavailable through the National Center for Biotechnology Information. TheBLAST algorithm parameters W, T, and X determine the sensitivity andspeed of the alignment. The BLASTN program (for nucleotide sequences)uses as defaults a wordlength (W) of 11, an expectation (E) or 10, M=5,N=−4 and a comparison of both strands. For amino acid sequences, theBLASTP program uses as defaults a wordlength of 3, and expectation (E)of 10, and the BLOSUM62 scoring matrix (see Henikoff and Henikoff (1989)Proc. Natl. Acad. Sci. USA 89:10915) alignments (B) of 50, expectation(E) of 10, M=5, N=4, and a comparison of both strands. The BLASTalgorithm is typically performed with the “low complexity” filter turnedoff.

The BLAST algorithm also performs a statistical analysis of thesimilarity between two sequences (see, e.g., Karlin and Altschul (1993)Proc. Natl. Acad. Sci. USA 90:5873-5787). One measure of similarityprovided by the BLAST algorithm is the smallest sum probability (P(N)),which provides an indication of the probability by which a match betweentwo nucleotide or amino acid sequences would occur by chance. Forexample, a nucleic acid is considered similar to a reference sequence ifthe smallest sum probability in a comparison of the test nucleic acid tothe reference nucleic acid is less than about 0.2, more preferably lessthan about 0.01, and most preferably less than about 0.001.

The phrase “selectively (or specifically) hybridizes to” refers to thebinding, duplexing, or hybridizing of a molecule only to a particularnucleotide sequence under stringent hybridization conditions when thatsequence is present in a complex mixture (including but not limited to,total cellular or library DNA or RNA).

The phrase “stringent hybridization conditions” refers to conditions oflow ionic strength and high temperature as is known in the art.Typically, under stringent conditions a probe will hybridize to itstarget subsequence in a complex mixture of nucleic acid (including butnot limited to, total cellular or library DNA or RNA) but does nothybridize to other sequences in the complex mixture. Stringentconditions are sequence-dependent and will be different in differentcircumstances. Longer sequences hybridize specifically at highertemperatures. An extensive guide to the hybridization of nucleic acidsis found in Tijssen, Techniques in Biochemistry and MolecularBiology—Hybridization with Nucleic Probes, “Overview of principles ofhybridization and the strategy of nucleic acid assays” (1993).Generally, stringent conditions are selected to be about 5-10° C. lowerthan the thermal melting point (T_(m)) for the specific sequence at adefined ionic strength pH. The T_(m) is the temperature (under definedionic strength, pH, and nucleic concentration) at which 50% of theprobes complementary to the target hybridize to the target sequence atequilibrium (as the target sequences are present in excess, at T_(m),50% of the probes are occupied at equilibrium). Stringent conditions maybe those in which the salt concentration is less than about 1.0 M sodiumion, typically about 0.01 to 1.0 M sodium ion concentration (or othersalts) at pH 7.0 to 8.3 and the temperature is at least about 30° C. forshort probes (including but not limited to, 10 to 50 nucleotides) and atleast about 60° C. for long probes (including but not limited to,greater than 50 nucleotides). Stringent conditions may also be achievedwith the addition of destabilizing agents such as formamide. Forselective or specific hybridization, a positive signal may be at leasttwo times background, optionally 10 times background hybridization.Exemplary stringent hybridization conditions can be as following: 50%formamide, 5×SSC, and 1% SDS, incubating at 42° C., or 5×SSC, 1% SDS,incubating at 65° C., with wash in 0.2×SSC, and 0.1% SDS at 65° C. Suchwashes can be performed for 5, 15, 30, 60, 120, or more minutes.

As used herein, the term “eukaryote” refers to organisms belonging tothe phylogenetic domain Eucarya such as animals (including but notlimited to, mammals, insects, reptiles, birds, etc.), ciliates, plants(including but not limited to, monocots, dicots, algae, etc.), fungi,yeasts, flagellates, microsporidia, protists, etc.

As used herein, the term “non-eukaryote” refers to non-eukaryoticorganisms. For example, a non-eukaryotic organism can belong to theEubacteria (including but not limited to, Escherichia coli, Thermusthermophilus, Bacillus stearothermophilus, Pseudomonas fluorescens,Pseudomonas aeruginosa, Pseudomonas putida, etc.) phylogenetic domain,or the Archaea (including but not limited to, Methanococcus jannaschii,Methanobacterium thermoautotrophicum, Halobacterium such as Haloferaxvolcanii and Halobacterium species NRC-1, Archaeoglobus fulgidus,Pyrococcus furiosus, Pyrococcus horikoshii, Aeuropyrum pernix, etc.)phylogenetic domain.

The term “subject” as used herein, refers to an animal, preferably amammal, most preferably a human, who is the object of treatment,observation or experiment.

The term “effective amount” as used herein refers to that amount of the(modified) non-natural amino acid polypeptide being administered whichwill relieve to some extent one or more of the symptoms of the disease,condition or disorder being treated. Compositions containing the(modified) non-natural amino acid polypeptide described herein can beadministered for prophylactic, enhancing, and/or therapeutic treatments.

The terms “enhance” or “enhancing” means to increase or prolong eitherin potency or duration a desired effect. Thus, in regard to enhancingthe effect of therapeutic agents, the term “enhancing” refers to theability to increase or prolong, either in potency or duration, theeffect of other therapeutic agents on a system. An “enhancing-effectiveamount,” as used herein, refers to an amount adequate to enhance theeffect of another therapeutic agent in a desired system. When used in apatient, amounts effective for this use will depend on the severity andcourse of the disease, disorder or condition, previous therapy, thepatient's health status and response to the drugs, and the judgment ofthe treating physician.

The term “modified,” as used herein refers to the presence of apost-translational modification on a polypeptide. The form “(modified)”term means that the polypeptides being discussed are optionallymodified, that is, the polypeptides under discussion can be modified orunmodified.

The term “post-translationally modified” and “modified” refers to anymodification of a natural or non-natural amino acid that occurs to suchan amino acid after it has been incorporated into a polypeptide chain.The term encompasses, by way of example only, co-translational in vivomodifications, post-translational in vivo modifications, andpost-translational in vitro modifications.

In prophylactic applications, compositions containing the (modified)non-natural amino acid polypeptide are administered to a patientsusceptible to or otherwise at risk of a particular disease, disorder orcondition. Such an amount is defined to be a “prophylactically effectiveamount.” In this use, the precise amounts also depend on the patient'sstate of health, weight, and the like. It is considered well within theskill of the art for one to determine such prophylactically effectiveamounts by routine experimentation (e.g., a dose escalation clinicaltrial).

The term “protected” refers to the presence of a “protecting group” ormoiety that prevents reaction of the chemically reactive functionalgroup under certain reaction conditions. The protecting group will varydepending on the type of chemically reactive group being protected. Forexample, if the chemically reactive group is an amine or a hydrazide,the protecting group can be selected from the group oftert-butyloxycarbonyl (t-Boc) and 9-fluorenylmethoxycarbonyl (Fmoc). Ifthe chemically reactive group is a thiol, the protecting group can beorthopyridyldisulfide. If the chemically reactive group is a carboxylicacid, such as butanoic or propionic acid, or a hydroxyl group, theprotecting group can be benzyl or an alkyl group such as methyl, ethyl,or tert-butyl. Other protecting groups known in the art may also be usedin or with the methods and compositions described herein.

By way of example only, blocking/protecting groups may be selected from:

Other protecting groups are described in Greene and Wuts, ProtectiveGroups in Organic Synthesis, 3rd Ed., John Wiley & Sons, New York, N.Y.,1999, which is incorporated herein by reference in its entirety.

In therapeutic applications, compositions containing the (modified)non-natural amino acid polypeptide are administered to a patient alreadysuffering from a disease, condition or disorder, in an amount sufficientto cure or at least partially arrest the symptoms of the disease,disorder or condition. Such an amount is defined to be a“therapeutically effective amount,” and will depend on the severity andcourse of the disease, disorder or condition, previous therapy, thepatient's health status and response to the drugs, and the judgment ofthe treating physician. It is considered well within the skill of theart for one to determine such therapeutically effective amounts byroutine experimentation (e.g., a dose escalation clinical trial).

The term “treating” is used to refer to either prophylactic and/ortherapeutic treatments.

Unless otherwise indicated, conventional methods of mass spectroscopy,NMR, HPLC, protein chemistry, biochemistry, recombinant DNA techniquesand pharmacology, within the skill of the art are employed.

DETAILED DESCRIPTION

I. Introduction

hGH molecules comprising at least one unnatural amino acid are providedin the invention. In certain embodiments of the invention, the hGHpolypeptide with at least one unnatural amino acid includes at least onepost-translational modification. In one embodiment, the at least onepost-translational modification comprises attachment of a moleculeincluding but not limited to, a label, a dye, a polymer, a water-solublepolymer, a derivative of polyethylene glycol, a photocrosslinker, acytotoxic compound, a drug, an affinity label, a photoaffinity label, areactive compound, a resin, a second protein or polypeptide orpolypeptide analog, an antibody or antibody fragment, a metal chelator,a cofactor, a fatty acid, a carbohydrate, a polynucleotide, a DNA, aRNA, an antisense polynucleotide, an inhibitory ribonucleic acid, abiomaterial, a nanoparticle, a spin label, a fluorophore, ametal-containing moiety, a radioactive moiety, a novel functional group,a group that covalently or noncovalently interacts with other molecules,a photocaged moiety, a photoisomerizable moiety, biotin, a derivative ofbiotin, a biotin analogue, a moiety incorporating a heavy atom, achemically cleavable group, a photocleavable group, an elongated sidechain, a carbon-linked sugar, a redox-active agent, an amino thioacid, atoxic moiety, an isotopically labeled moiety, a biophysical probe, aphosphorescent group, a chemiluminescent group, an electron dense group,a magnetic group, an intercalating group, a chromophore, an energytransfer agent, a biologically active agent, a detectable label, a smallmolecule, or any combination of the above or any other desirablecompound or substance, comprising a second reactive group to at leastone unnatural amino acid comprising a first reactive group utilizingchemistry methodology that is known to one of ordinary skill in the artto be suitable for the particular reactive groups. For example, thefirst reactive group is an alkynyl moiety (including but not limited to,in the unnatural amino acid p-propargyloxyphenylalanine, where thepropargyl group is also sometimes referred to as an acetylene moiety)and the second reactive group is an azido moiety, and [3+2]cycloaddition chemistry methodologies are utilized. In another example,the first reactive group is the azido moiety (including but not limitedto, in the unnatural amino acid p-azido-L-phenylalanine) and the secondreactive group is the alkynyl moiety. In certain embodiments of themodified hGH polypeptide of the present invention, at least oneunnatural amino acid (including but not limited to, unnatural amino acidcontaining a keto functional group) comprising at least onepost-translational modification, is used where the at least onepost-translational modification comprises a saccharide moiety. Incertain embodiments, the post-translational modification is made in vivoin a eukaryotic cell or in a non-eukaryotic cell.

In certain embodiments, the protein includes at least onepost-translational modification that is made in vivo by one host cell,where the post-translational modification is not normally made byanother host cell type. In certain embodiments, the protein includes atleast one post-translational modification that is made in vivo by aeukaryotic cell, where the post-translational modification is notnormally made by a non-eukaryotic cell. Examples of post-translationalmodifications include, but are not limited to, acetylation, acylation,lipid-modification, palmitoylation, palmitate addition, phosphorylation,glycolipid-linkage modification, and the like. In one embodiment, thepost-translational modification comprises attachment of anoligosaccharide to an asparagine by a GlcNAc-asparagine linkage(including but not limited to, where the oligosaccharide comprises(GlcNAc-Man)₂-Man-GlcNAc-GlcNAc, and the like). In another embodiment,the post-translational modification comprises attachment of anoligosaccharide (including but not limited to, Gal-GalNAc, Gal-GlcNAc,etc.) to a serine or threonine by a GalNAc-serine, a GalNAc-threonine, aGlcNAc-serine, or a GlcNAc-threonine linkage. In certain embodiments, aprotein or polypeptide of the invention can comprise a secretion orlocalization sequence, an epitope tag, a FLAG tag, a polyhistidine tag,a GST fusion, and/or the like.

The protein or polypeptide of interest can contain at least one, atleast two, at least three, at least four, at least five, at least six,at least seven, at least eight, at least nine, or ten or more unnaturalamino acids. The unnatural amino acids can be the same or different, forexample, there can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or more differentsites in the protein that comprise 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or moredifferent unnatural amino acids. In certain embodiments, at least one,but fewer than all, of a particular amino acid present in a naturallyoccurring version of the protein is substituted with an unnatural aminoacid.

The present invention provides methods and compositions based on membersof the GH supergene family, in particular hGH, comprising at least onenon-naturally encoded amino acid. Introduction of at least onenon-naturally encoded amino acid into a GH supergene family member canallow for the application of conjugation chemistries that involvespecific chemical reactions, including, but not limited to, with one ormore non-naturally encoded amino acids while not reacting with thecommonly occurring 20 amino acids. In some embodiments, the GH supergenefamily member comprising the non-naturally encoded amino acid is linkedto a water soluble polymer, such as polyethylene glycol (PEG), via theside chain of the non-naturally encoded amino acid. This inventionprovides a highly efficient method for the selective modification ofproteins with PEG derivatives, which involves the selectiveincorporation of non-genetically encoded amino acids, including but notlimited to, those amino acids containing functional groups orsubstituents not found in the 20 naturally incorporated amino acids,including but not limited to a ketone, an azide or acetylene moiety,into proteins in response to a selector codon and the subsequentmodification of those amino acids with a suitably reactive PEGderivative. Once incorporated, the amino acid side chains can then bemodified by utilizing chemistry methodologies known to those of ordinaryskill in the art to be suitable for the particular functional groups orsubstituents present in the naturally encoded amino acid. Knownchemistry methodologies of a wide variety are suitable for use in thepresent invention to incorporate a water soluble polymer into theprotein. Such methodologies include but are not limited to a Huisgen[3+2] cycloaddition reaction (see, e.g., Padwa, A. in ComprehensiveOrganic Synthesis, Vol. 4, (1991) Ed. Trost, B. M., Pergamon, Oxford, p.1069-1109; and, Huisgen, R. in 1,3-Dipolar Cycloaddition Chemistry,(1984) Ed. Padwa, A., Wiley, New York, p. 1-176) with, including but notlimited to, acetylene or azide derivatives, respectively.

Because the Huisgen [3+2] cycloaddition method involves a cycloadditionrather than a nucleophilic substitution reaction, proteins can bemodified with extremely high selectivity. The reaction can be carriedout at room temperature in aqueous conditions with excellentregioselectivity (1.4>1.5) by the addition of catalytic amounts of Cu(I)salts to the reaction mixture. See, e.g., Tornoe, et al., (2002) Org.Chem. 67:3057-3064; and, Rostovtsev, et al., (2002) Angew. Chem. Int.Ed. 41:2596-2599; and WO 03/101972. A molecule that can be added to aprotein of the invention through a [3+2] cycloaddition includesvirtually any molecule with a suitable functional group or substituentincluding but not limited to an azido or acetylene derivative. Thesemolecules can be added to an unnatural amino acid with an acetylenegroup, including but not limited to, p-propargyloxyphenylalanine, orazido group, including but not limited to p-azido-phenylalanine,respectively.

The five-membered ring that results from the Huisgen [3+2] cycloadditionis not generally reversible in reducing environments and is stableagainst hydrolysis for extended periods in aqueous environments.Consequently, the physical and chemical characteristics of a widevariety of substances can be modified under demanding aqueous conditionswith the active PEG derivatives of the present invention. Even moreimportant, because the azide and acetylene moieties are specific for oneanother (and do not, for example, react with any of the 20 common,genetically-encoded amino acids), proteins can be modified in one ormore specific sites with extremely high selectivity.

The invention also provides water soluble and hydrolytically stablederivatives of PEG derivatives and related hydrophilic polymers havingone or more acetylene or azide moieties. The PEG polymer derivativesthat contain acetylene moieties are highly selective for coupling withazide moieties that have been introduced selectively into proteins inresponse to a selector codon. Similarly, PEG polymer derivatives thatcontain azide moieties are highly selective for coupling with acetylenemoieties that have been introduced selectively into proteins in responseto a selector codon.

More specifically, the azide moieties comprise, but are not limited to,alkyl azides, aryl azides and derivatives of these azides. Thederivatives of the alkyl and aryl azides can include other substituentsso long as the acetylene-specific reactivity is maintained. Theacetylene moieties comprise alkyl and aryl acetylenes and derivatives ofeach. The derivatives of the alkyl and aryl acetylenes can include othersubstituents so long as the azide-specific reactivity is maintained.

The present invention provides conjugates of substances having a widevariety of functional groups, substituents or moieties, with othersubstances including but not limited to a label; a dye; a polymer; awater-soluble polymer; a derivative of polyethylene glycol; aphotocrosslinker; a cytotoxic compound; a drug; an affinity label; aphotoaffinity label; a reactive compound; a resin; a second protein orpolypeptide or polypeptide analog; an antibody or antibody fragment; ametal chelator; a cofactor; a fatty acid; a carbohydrate; apolynucleotide; a DNA; a RNA; an antisense polynucleotide; an inhibitoryribonucleic acid; a biomaterial; a nanoparticle; a spin label; afluorophore, a metal-containing moiety; a radioactive moiety; a novelfunctional group; a group that covalently or noncovalently interactswith other molecules; a photocaged moiety; a photoisomerizable moiety;biotin; a derivative of biotin; a biotin analogue; a moietyincorporating a heavy atom; a chemically cleavable group; aphotocleavable group; an elongated side chain; a carbon-linked sugar; aredox-active agent; an amino thioacid; a toxic moiety; an isotopicallylabeled moiety; a biophysical probe; a phosphorescent group; achemiluminescent group; an electron dense group; a magnetic group; anintercalating group; a chromophore; an energy transfer agent; abiologically active agent; a detectable label; a small molecule; or anycombination of the above, or any other desirable compound or substance).The present invention also includes conjugates of substances havingazide or acetylene moieties with PEG polymer derivatives having thecorresponding acetylene or azide moieties. For example, a PEG polymercontaining an azide moiety can be coupled to a biologically activemolecule at a position in the protein that contains a non-geneticallyencoded amino acid bearing an acetylene functionality. The linkage bywhich the PEG and the biologically active molecule are coupled includesbut is not limited to the Huisgen [3+2] cycloaddition product.

It is well established in the art that PEG can be used to modify thesurfaces of biomaterials (see, e.g., U.S. Pat. No. 6,610,281; Mehvar,R., J. Pharmaceut. Sci., 3(1):125-136 (2000) which are incorporated byreference herein). The invention also includes biomaterials comprising asurface having one or more reactive azide or acetylene sites and one ormore of the azide- or acetylene-containing polymers of the inventioncoupled to the surface via the Huisgen [3+2] cycloaddition linkage.Biomaterials and other substances can also be coupled to the azide- oracetylene-activated polymer derivatives through a linkage other than theazide or acetylene linkage, such as through a linkage comprising acarboxylic acid, amine, alcohol or thiol moiety, to leave the azide oracetylene moiety available for subsequent reactions.

The invention includes a method of synthesizing the azide- andacetylene-containing polymers of the invention. In the case of theazide-containing PEG derivative, the azide can be bonded directly to acarbon atom of the polymer. Alternatively, the azide-containing PEGderivative can be prepared by attaching a linking agent that has theazide moiety at one terminus to a conventional activated polymer so thatthe resulting polymer has the azide moiety at its terminus. In the caseof the acetylene-containing PEG derivative, the acetylene can be bondeddirectly to a carbon atom of the polymer. Alternatively, theacetylene-containing PEG derivative can be prepared by attaching alinking agent that has the acetylene moiety at one terminus to aconventional activated polymer so that the resulting polymer has theacetylene moiety at its terminus.

More specifically, in the case of the azide-containing PEG derivative, awater soluble polymer having at least one active hydroxyl moietyundergoes a reaction to produce a substituted polymer having a morereactive moiety, such as a mesylate, tresylate, tosylate or halogenleaving group, thereon. The preparation and use of PEG derivativescontaining sulfonyl acid halides, halogen atoms and other leaving groupsare well known to the skilled artisan. The resulting substituted polymerthen undergoes a reaction to substitute for the more reactive moiety anazide moiety at the terminus of the polymer. Alternatively, a watersoluble polymer having at least one active nucleophilic or electrophilicmoiety undergoes a reaction with a linking agent that has an azide atone terminus so that a covalent bond is formed between the PEG polymerand the linking agent and the azide moiety is positioned at the terminusof the polymer. Nucleophilic and electrophilic moieties, includingamines, thiols, hydrazides, hydrazines, alcohols, carboxylates,aldehydes, ketones, thioesters and the like, are well known to theskilled artisan.

More specifically, in the case of the acetylene-containing PEGderivative, a water soluble polymer having at least one active hydroxylmoiety undergoes a reaction to displace a halogen or other activatedleaving group from a precursor that contains an acetylene moiety.Alternatively, a water soluble polymer having at least one activenucleophilic or electrophilic moiety undergoes a reaction with a linkingagent that has an acetylene at one terminus so that a covalent bond isformed between the PEG polymer and the linking agent and the acetylenemoiety is positioned at the terminus of the polymer. The use of halogenmoieties, activated leaving group, nucleophilic and electrophilicmoieties in the context of organic synthesis and the preparation and useof PEG derivatives is well established to practitioners in the art.

The invention also provides a method for the selective modification ofproteins to add other substances to the modified protein, including butnot limited to water soluble polymers such as PEG and PEG derivativescontaining an azide or acetylene moiety. The azide- andacetylene-containing PEG derivatives can be used to modify theproperties of surfaces and molecules where biocompatibility, stability,solubility and lack of immunogenicity are important, while at the sametime providing a more selective means of attaching the PEG derivativesto proteins than was previously known in the art.

II. Growth Hormone Supergene Family

The following proteins include those encoded by genes of the growthhormone (GH) supergene family (Bazan, F., Immunology Today 11: 350-354(1991); Bazan, J. F. Science 257: 410-411 (1992); Mott, H. R. andCampbell, I. D., Current Opinion in Structural Biology 5: 114-121(1995); Silvennoinen, O. and Ihle, J. N., SIGNALLING BY THEHEMATOPOIETIC CYTOKINE RECEPTORS (1996)): growth hormone, prolactin,placental lactogen, erythropoietin (EPO), thrombopoietin (TPO),interleukin-2 (IL-2), IL-3, IL-4, IL-5, IL-6, IL-7, IL-9, IL-10, IL-11,IL-12 (p35 subunit), IL-13, IL-15, oncostatin M, ciliary neurotrophicfactor (CNTF), leukemia inhibitory factor (LIF), alpha interferon, betainterferon, epsilon interferon, gamma interferon, omega interferon, tauinterferon, granulocyte-colony stimulating factor (G-CSF),granulocyte-macrophage colony stimulating factor (GM-CSF), macrophagecolony stimulating factor (M-CSF) and cardiotrophin-1 (CT-1) (“the GHsupergene family”). It is anticipated that additional members of thisgene family will be identified in the future through gene cloning andsequencing. Members of the GH supergene family have similar secondaryand tertiary structures, despite the fact that they generally havelimited amino acid or DNA sequence identity. The shared structuralfeatures allow new members of the gene family to be readily identifiedand the non-natural amino acid methods and compositions described hereinsimilarly applied. Given the extent of structural homology among themembers of the GH supergene family, non-naturally encoded amino acidsmay be incorporated into any members of the GH supergene family usingthe present invention. Each member of this family of proteins comprisesa four helical bundle, the general structure of which is shown inFIG. 1. The general structures of family members hGH, EPO, IFNα-2, andG-CSF are shown in FIGS. 2, 3, 4, and 5, respectively.

Structures of a number of cytokines, including G-CSF (Zink et al., FEBSLett. 314:435 (1992); Zink et al., Biochemistry 33:8453 (1994); Hill etal., Proc. Natl. Acad. Sci. USA 90:5167 (1993)), GM-CSF (Diederichs, K.,et al. Science 154: 1779-1782 (1991); Walter et al., J. Mol. Biol.224:1075-1085 (1992)), IL-2 (Bazan, J. F. Science 257: 410-411 (1992);McKay, D. B. Science 257: 412 (1992)), IL-4 (Redfield et al.,Biochemistry 30: 11029-11035 (1991); Powers et al., Science256:1673-1677 (1992)), and IL-5 (Milburn et al., Nature 363: 172-176(1993)) have been determined by X-ray diffraction and NMR studies andshow striking conservation with the GH structure, despite a lack ofsignificant primary sequence homology. IFN is considered to be a memberof this family based upon modeling and other studies (Lee et al., J.Growth hormone Cytokine Res. 15:341 (1995); Murgolo et al., Proteins17:62 (1993); Radhakrishnan et al., Structure 4:1453 (1996); Klaus etal., J. Mol. Biol. 274:661 (1997)). EPO is considered to be a member ofthis family based upon modeling and mutagenesis studies (Boissel et al.,J. Biol. Chem. 268: 15983-15993 (1993); Wen et al., J. Biol. Chem. 269:22839-22846 (1994)). All of the above cytokines and growth factors arenow considered to comprise one large gene family.

In addition to sharing similar secondary and tertiary structures,members of this family share the property that they must oligomerizecell surface receptors to activate intracellular signaling pathways.Some GH family members, including but not limited to; GH and EPO, bind asingle type of receptor and cause it to form homodimers. Other familymembers, including but not limited to, IL-2, IL-4, and IL-6, bind morethan one type of receptor and cause the receptors to form heterodimersor higher order aggregates (Davis et al., (1993), Science 260:1805-1808; Paonessa et al., (1995), EMBO J. 14: 1942-1951; Mott andCampbell, Current Opinion in Structural Biology 5: 114-121 (1995)).Mutagenesis studies have shown that, like GH, these other cytokines andgrowth factors contain multiple receptor binding sites, typically two,and bind their cognate receptors sequentially (Mott and Campbell,Current Opinion in Structural Biology 5: 114-121 (1995); Matthews etal., (1996) Proc. Natl. Acad. Sci. USA 93: 9471-9476). Like GH, theprimary receptor binding sites for these other family members occurprimarily in the four alpha helices and the A-B loop. The specific aminoacids in the helical bundles that participate in receptor binding differamongst the family members. Most of the cell surface receptors thatinteract with members of the GH supergene family are structurallyrelated and comprise a second large multi-gene family. See, e.g. U.S.Pat. No. 6,608,183, which is incorporated by reference herein.

A general conclusion reached from mutational studies of various membersof the GH supergene family is that the loops joining the alpha helicesgenerally tend to not be involved in receptor binding. In particular theshort B-C loop appears to be non-essential for receptor binding in most,if not all, family members. For this reason, the B-C loop may besubstituted with non-naturally encoded amino acids as described hereinin members of the GH supergene family. The A-B loop, the C-D loop (andD-E loop of interferon/IL-10-like members of the GH superfamily) mayalso be substituted with a non-naturally-occurring amino acid. Aminoacids proximal to helix A and distal to the final helix also tend not tobe involved in receptor binding and also may be sites for introducingnon-naturally-occurring amino acids. In some embodiments, anon-naturally encoded amino acid is substituted at any position within aloop structure, including but not limited to, the first 1, 2, 3, 4, 5,6, 7, or more amino acids of the A-B, B-C, C-D or D-E loop. In someembodiments, one or more non-naturally encoded amino acids aresubstituted within the last 1, 2, 3, 4, 5, 6, 7, or more amino acids ofthe A-B, B-C, C-D or D-E loop.

Certain members of the GH family, including but not limited to, EPO,IL-2, IL-3, IL-4, IL-6, G-CSF, GM-CSF, TPO, IL-10, IL-12 p35, IL-13,IL-15 and beta interferon contain N-linked and/or O-linked sugars. Theglycosylation sites in the proteins occur almost exclusively in the loopregions and not in the alpha helical bundles. Because the loop regionsgenerally are not involved in receptor binding and because they aresites for the covalent attachment of sugar groups, they may be usefulsites for introducing non-naturally-occurring amino acid substitutionsinto the proteins. Amino acids that comprise the N- and O-linkedglycosylation sites in the proteins may be sites fornon-naturally-occurring amino acid substitutions because these aminoacids are surface-exposed. Therefore, the natural protein can toleratebulky sugar groups attached to the proteins at these sites and theglycosylation sites tend to be located away from the receptor bindingsites.

Additional members of the GH supergene family are likely to bediscovered in the future. New members of the GH supergene family can beidentified through computer-aided secondary and tertiary structureanalyses of the predicted protein sequences. Members of the GH supergenefamily typically possess four or five amphipathic helices joined bynon-helical amino acids (the loop regions). The proteins may contain ahydrophobic signal sequence at their N-terminus to promote secretionfrom the cell. Such later discovered members of the GH supergene familyalso are included within this invention. A related application isInternational Patent Application entitled “Modified Four Helical BundlePolypeptides and Their Uses” (Attorney Docket number AMBX-0028.00PCT;PCT/US2005/______), filed Jan. 28, 2005, which is incorporated byreference herein.

Thus, the description of the growth hormone supergene family is providedfor illustrative purposes and by way of example only and not as a limiton the scope of the methods, compositions, strategies and techniquesdescribed herein. Further, reference to GH polypeptides in thisapplication is intended to use the generic term as an example of anymember of the GH supergene family. Thus, it is understood that themodifications and chemistries described herein with reference to hGHpolypeptides or protein can be equally applied to any member of the GHsupergene family, including those specifically listed herein.

III. General Recombinant Nucleic Acid Methods for Use with the Invention

In numerous embodiments of the present invention, nucleic acids encodinga hGH polypeptide of interest will be isolated, cloned and often alteredusing recombinant methods. Such embodiments are used, including but notlimited to, for protein expression or during the generation of variants,derivatives, expression cassettes, or other sequences derived from a hGHpolypeptide. In some embodiments, the sequences encoding thepolypeptides of the invention are operably linked to a heterologouspromoter. Isolation of hGH and production of GH in host cells aredescribed in, e.g., U.S. Pat. Nos. 4,601,980, 4,604,359, 4,634,677,4,658,021, 4,898,830, 5,424,199, 5,795,745, 5,854,026, 5,849,535;6,004,931; 6,022,711; 6,143,523 and 6,608,183, which are incorporated byreference herein.

A nucleotide sequence encoding a hGH polypeptide comprising anon-naturally encoded amino acid may be synthesized on the basis of theamino acid sequence of the parent polypeptide, including but not limitedto, having the amino acid sequence shown in SEQ ID NO: 2 (hGH) and thenchanging the nucleotide sequence so as to effect introduction (i.e.,incorporation or substitution) or removal (i.e., deletion orsubstitution) of the relevant amino acid residue(s). The nucleotidesequence may be conveniently modified by site-directed mutagenesis inaccordance with conventional methods. Alternatively, the nucleotidesequence may be prepared by chemical synthesis, including but notlimited to, by using an oligonucleotide synthesizer, whereinoligonucleotides are designed based on the amino acid sequence of thedesired polypeptide, and preferably selecting those codons that arefavored in the host cell in which the recombinant polypeptide will beproduced. For example, several small oligonucleotides coding forportions of the desired polypeptide may be synthesized and assembled byPCR, ligation or ligation chain reaction. See, e.g., Barany, et al.,Proc. Natl. Acad. Sci. 88: 189-193 (1991); U.S. Pat. No. 6,521,427 whichare incorporated by reference herein.

This invention utilizes routine techniques in the field of recombinantgenetics. Basic texts disclosing the general methods of use in thisinvention include Sambrook et al., Molecular Cloning, A LaboratoryManual (3rd ed. 2001); Kriegler, Gene Transfer and Expression: ALaboratory Manual (1990); and Current Protocols in Molecular Biology(Ausubel et al., eds., 1994)).

General texts which describe molecular biological techniques includeBerger and Kimmel, Guide to Molecular Cloning Techniques, Methods inEnzymology volume 152 Academic Press, Inc., San Diego, Calif. (Berger);Sambrook et al., Molecular Cloning—A Laboratory Manual (2nd Ed.), Vol.1-3, Cold Spring Harbor Laboratory, Cold Spring Harbor, N.Y., 1989(“Sambrook”) and Current Protocols in Molecular Biology, F. M. Ausubelet al., eds., Current Protocols, a joint venture between GreenePublishing Associates, Inc. and John Wiley & Sons, Inc., (supplementedthrough 1999) (“Ausubel”)). These texts describe mutagenesis, the use ofvectors, promoters and many other relevant topics related to, includingbut not limited to, the generation of genes that include selector codonsfor production of proteins that include unnatural amino acids,orthogonal tRNAs, orthogonal synthetases, and pairs thereof.

Various types of mutagenesis are used in the invention for a variety ofpurposes, including but not limited to, to produce libraries of tRNAs,to produce libraries of synthetases, to produce selector codons, toinsert selector codons that encode unnatural amino acids in a protein orpolypeptide of interest. They include but are not limited tosite-directed, random point mutagenesis, homologous recombination, DNAshuffling or other recursive mutagenesis methods, chimeric construction,mutagenesis using uracil containing templates, oligonucleotide-directedmutagenesis, phosphorothioate-modified DNA mutagenesis, mutagenesisusing gapped duplex DNA or the like, or any combination thereof.Additional suitable methods include point mismatch repair, mutagenesisusing repair-deficient host strains, restriction-selection andrestriction-purification, deletion mutagenesis, mutagenesis by totalgene synthesis, double-strand break repair, and the like. Mutagenesis,including but not limited to, involving chimeric constructs, are alsoincluded in the present invention. In one embodiment, mutagenesis can beguided by known information of the naturally occurring molecule oraltered or mutated naturally occurring molecule, including but notlimited to, sequence, sequence comparisons, physical properties, crystalstructure or the like.

The texts and examples found herein describe these procedures.Additional information is found in the following publications andreferences cited within: Ling et al., Approaches to DNA mutagenesis: anoverview, Anal Biochem. 254(2): 157-178 (1997); Dale et al.,Oligonucleotide-directed random mutagenesis using the phosphorothioatemethod, Methods Mol. Biol. 57:369-374 (1996); Smith, In vitromutagenesis, Ann. Rev. Genet. 19:423-462 (1985); Botstein & Shortle,Strategies and applications of in vitro mutagenesis, Science229:1193-1201 (1985); Carter, Site-directed mutagenesis, Biochem. J.237:1-7 (1986); Kunkel, The efficiency of oligonucleotide directedmutagenesis, in Nucleic Acids & Molecular Biology (Eckstein, F. andLilley, D. M. J. eds., Springer Verlag, Berlin) (1987); Kunkel, Rapidand efficient site-specific mutagenesis without phenotypic selection,Proc. Natl. Acad. Sci. USA 82:488-492 (1985); Kunkel et al., Rapid andefficient site-specific mutagenesis without phenotypic selection,Methods in Enzymol. 154, 367-382 (1987); Bass et al., Mutant Trprepressors with new DNA-binding specificities, Science 242:240-245(1988); Methods in Enzymol. 100: 468-500 (1983); Methods in Enzymol.154: 329-350 (1987); Zoller & Smith, Oligonucleotide-directedmutagenesis using M13-derived vectors: an efficient and generalprocedure for the production of point mutations in any DNA fragment,Nucleic Acids Res. 10:6487-6500 (1982); Zoller & Smith,Oligonucleotide-directed mutagenesis of DNA fragments cloned into M13vectors, Methods in Enzymol. 100:468-500 (1983); Zoller & Smith,Oligonucleotide-directed mutagenesis: a simple method using twooligonucleotide primers and a single-stranded DNA template, Methods inEnzymol. 154:329-350 (1987); Taylor et al., The use ofphosphorothioate-modified DNA in restriction enzyme reactions to preparenicked DNA, Nucl. Acids Res. 13: 8749-8764 (1985); Taylor et al., Therapid generation of oligonucleotide-directed mutations at high frequencyusing phosphorothioate-modified DNA, Nucl. Acids Res. 13: 8765-8787(1985); Nakamaye & Eckstein, Inhibition of restriction endonuclease NciI cleavage by phosphorothioate groups and its application tooligonucleotide-directed mutagenesis, Nucl. Acids Res. 14: 9679-9698(1986); Sayers et al., Y-T Exonucleases in phosphorothioate-basedoligonucleotide-directed mutagenesis, Nucl. Acids Res. 16:791-802(1988); Sayers et al., Strand specific cleavage ofphosphorothioate-containing DNA by reaction with restrictionendonucleases in the presence of ethidium bromide, (1988) Nucl. AcidsRes. 16: 803-814; Kramer et al., The gapped duplex DNA approach tooligonucleotide-directed mutation construction, Nucl. Acids Res. 12:9441-9456 (1984); Kramer & Fritz Oligonucleotide-directed constructionof mutations via gapped duplex DNA, Methods in Enzymol. 154:350-367(1987); Kramer et al., Improved enzymatic in vitro reactions in thegapped duplex DNA approach to oligonucleotide-directed construction ofmutations, Nucl. Acids Res. 16: 7207 (1988); Fritz et al.,Oligonucleotide-directed construction of mutations: a gapped duplex DNAprocedure without enzymatic reactions in vitro, Nucl. Acids Res. 16:6987-6999 (1988); Kramer et al., Point Mismatch Repair, Cell 38:879-887(1984); Carter et al., Improved oligonucleotide site-directedmutagenesis using M13 vectors, Nucl. Acids Res. 13: 4431-4443 (1985);Carter, Improved oligonucleotide-directed mutagenesis using M13 vectors,Methods in Enzymol. 154: 382-403 (1987); Eghtedarzadeh & Henikoff, Useof oligonucleotides to generate large deletions, Nucl. Acids Res. 14:5115 (1986); Wells et al., Importance of hydrogen-bond formation instabilizing the transition state of subtilisin, Phil. Trans. R. Soc.Lond. A 317: 415-423 (1986); Nambiar et al., Total synthesis and cloningof a gene coding for the ribonuclease S protein, Science 223: 1299-1301(1984); Sakamar and Khorana, Total synthesis and expression of a genefor the a-subunit of bovine rod outer segment guanine nucleotide-bindingprotein (transducin), Nucl. Acids Res. 14: 6361-6372 (1988); Wells etal., Cassette mutagenesis: an efficient method for generation ofmultiple mutations at defined sites, Gene 34:315-323 (1985); Grundströmet al., Oligonucleotide-directed mutagenesis by microscale ‘shot-gun’gene synthesis, Nucl. Acids Res. 13: 3305-3316 (1985); Mandecki,Oligonucleotide-directed double-strand break repair in plasmids ofEscherichia coli: a method for site-specific mutagenesis, Proc. Natl.Acad. Sci. USA, 83:7177-7181 (1986); Arnold, Protein engineering forunusual environments, Current Opinion in Biotechnology 4:450-455 (1993);Sieber, et al., Nature Biotechnology, 19:456-460 (2001); W. P. C.Stemmer, Nature 370, 389-91 (1994); and, I. A. Lorimer, I. Pastan,Nucleic Acids Res. 23, 3067-8 (1995). Additional details on many of theabove methods can be found in Methods in Enzymology Volume 154, whichalso describes useful controls for trouble-shooting problems withvarious mutagenesis methods.

The invention also relates to eukaryotic host cells, non-eukaryotic hostcells, and organisms for the in vivo incorporation of an unnatural aminoacid via orthogonal tRNA/RS pairs. Host cells are genetically engineered(including but not limited to, transformed, transduced or transfected)with the polynucleotides of the invention or constructs which include apolynucleotide of the invention, including but not limited to, a vectorof the invention, which can be, for example, a cloning vector or anexpression vector. The vector can be, for example, in the form of aplasmid, a bacterium, a virus, a naked polynucleotide, or a conjugatedpolynucleotide. The vectors are introduced into cells and/ormicroorganisms by standard methods including electroporation (From etal., Proc. Natl. Acad. Sci. USA 82, 5824 (1985), infection by viralvectors, high velocity ballistic penetration by small particles with thenucleic acid either within the matrix of small beads or particles, or onthe surface (Klein et al., Nature 327, 70-73 (1987)).

The engineered host cells can be cultured in conventional nutrient mediamodified as appropriate for such activities as, for example, screeningsteps, activating promoters or selecting transformants. These cells canoptionally be cultured into transgenic organisms. Other usefulreferences, including but not limited to for cell isolation and culture(e.g., for subsequent nucleic acid isolation) include Freshney (1994)Culture of Animal Cells, a Manual of Basic Technique, third edition,Wiley-Liss, New York and the references cited therein; Payne et al.(1992) Plant Cell and Tissue Culture in Liquid Systems John Wiley &Sons, Inc. New York, N.Y.; Gamborg and Phillips (eds.) (1995) PlantCell, Tissue and Organ Culture; Fundamental Methods Springer Lab Manual,Springer-Verlag (Berlin Heidelberg New York) and Atlas and Parks (eds.)The Handbook of Microbiological Media (1993) CRC Press, Boca Raton, Fla.

Several well-known methods of introducing target nucleic acids intocells are available, any of which can be used in the invention. Theseinclude: fusion of the recipient cells with bacterial protoplastscontaining the DNA, electroporation, projectile bombardment, andinfection with viral vectors (discussed further, below), etc. Bacterialcells can be used to amplify the number of plasmids containing DNAconstructs of this invention. The bacteria are grown to log phase andthe plasmids within the bacteria can be isolated by a variety of methodsknown in the art (see, for instance, Sambrook). In addition, a plethoraof kits are commercially available for the purification of plasmids frombacteria, (see, e.g., EasyPrep™, FlexiPrep™, both from PharmaciaBiotech; StrataClean™ from Stratagene; and, QIAprep™ from Qiagen). Theisolated and purified plasmids are then further manipulated to produceother plasmids, used to transfect cells or incorporated into relatedvectors to infect organisms. Typical vectors contain transcription andtranslation terminators, transcription and translation initiationsequences, and promoters useful for regulation of the expression of theparticular target nucleic acid. The vectors optionally comprise genericexpression cassettes containing at least one independent terminatorsequence, sequences permitting replication of the cassette ineukaryotes, or prokaryotes, or both, (including but not limited to,shuttle vectors) and selection markers for both prokaryotic andeukaryotic systems. Vectors are suitable for replication and integrationin prokaryotes, eukaryotes, or preferably both. See, Giliman & Smith,Gene 8:81 (1979); Roberts, et al., Nature, 328:731 (1987); Schneider,B., et al., Protein Expr. Purif. 6435:10 (1995); Ausubel, Sambrook,Berger (all supra). A catalogue of bacteria and bacteriophages usefulfor cloning is provided, e.g., by the ATCC, e.g., The ATCC Catalogue ofBacteria and Bacteriophage (1992) Gherna et al. (eds) published by theATCC. Additional basic procedures for sequencing, cloning and otheraspects of molecular biology and underlying theoretical considerationsare also found in Watson et al. (1992) Recombinant DNA Second EditionScientific American Books, NY. In addition, essentially any nucleic acid(and virtually any labeled nucleic acid, whether standard ornon-standard) can be custom or standard ordered from any of a variety ofcommercial sources, such as the Midland Certified Reagent Company(Midland, Tex. available on the World Wide Web at mcrc.com), The GreatAmerican Gene Company (Ramona, Calif. available on the World Wide Web atgenco.com), ExpressGen Inc. (Chicago, Ill. available on the World WideWeb at expressgen.com), Operon Technologies Inc. (Alameda, Calif.) andmany others.

Selector Codons

Selector codons of the invention expand the genetic codon framework ofprotein biosynthetic machinery. For example, a selector codon includes,but is not limited to, a unique three base codon, a nonsense codon, suchas a stop codon, including but not limited to, an amber codon (UAG), oran opal codon (UGA), an unnatural codon, a four or more base codon, arare codon, or the like. It is readily apparent to those of ordinaryskill in the art that there is a wide range in the number of selectorcodons that can be introduced into a desired gene, including but notlimited to, one or more, two or more, more than three, 4, 5, 6, 7, 8, 9,10 or more in a single polynucleotide encoding at least a portion of thehGH polypeptide.

In one embodiment, the methods involve the use of a selector codon thatis a stop codon for the incorporation of unnatural amino acids in vivoin a eukaryotic cell. For example, an O-tRNA is produced that recognizesthe stop codon, including but not limited to, UAG, and is aminoacylatedby an O-RS with a desired unnatural amino acid. This O-tRNA is notrecognized by the naturally occurring host's aminoacyl-tRNA synthetases.Conventional site-directed mutagenesis can be used to introduce the stopcodon, including but not limited to, TAG, at the site of interest in apolypeptide of interest. See, e.g., Sayers, J. R., et al. (1988), 5′,3′Exonuclease in phosphorothioate-based oligonucleotide-directedmutagenesis. Nucleic Acids Res, 791-802. When the O-RS, O-tRNA and thenucleic acid that encodes the polypeptide of interest are combined invivo, the unnatural amino acid is incorporated in response to the UAGcodon to give a polypeptide containing the unnatural amino acid at thespecified position.

The incorporation of unnatural amino acids in vivo can be done withoutsignificant perturbation of the eukaryotic host cell. For example,because the suppression efficiency for the UAG codon depends upon thecompetition between the O-tRNA, including but not limited to, the ambersuppressor tRNA, and a eukaryotic release factor (including but notlimited to, eRF) (which binds to a stop codon and initiates release ofthe growing peptide from the ribosome), the suppression efficiency canbe modulated by, including but not limited to, increasing the expressionlevel of O-tRNA, and/or the suppressor tRNA.

Selector codons also comprise extended codons, including but not limitedto, four or more base codons, such as, four, five, six or more basecodons. Examples of four base codons include, including but not limitedto, AGGA, CUAG, UAGA, CCCU and the like. Examples of five base codonsinclude, but are not limited to, AGGAC, CCCCU, CCCUC, CUAGA, CUACU,UAGGC and the like. A feature of the invention includes using extendedcodons based on frameshift suppression. Four or more base codons caninsert, including but not limited to, one or multiple unnatural aminoacids into the same protein. For example, in the presence of mutatedO-tRNAs, including but not limited to, a special frameshift suppressortRNAs, with anticodon loops, for example, with at least 8-10 ntanticodon loops, the four or more base codon is read as single aminoacid. In other embodiments, the anticodon loops can decode, includingbut not limited to, at least a four-base codon, at least a five-basecodon, or at least a six-base codon or more. Since there are 256possible four-base codons, multiple unnatural amino acids can be encodedin the same cell using a four or more base codon. See, Anderson et al.,(2002) Exploring the Limits of Codon and Anticodon Size, Chemistry andBiology, 9:237-244; Magliery, (2001) Expanding the Genetic Code:Selection of Efficient Suppressors of Four-base Codons andIdentification of “Shifty” Four-base Codons with a Library Approach inEscherichia coli, J. Mol. Biol. 307: 755-769.

For example, four-base codons have been used to incorporate unnaturalamino acids into proteins using in vitro biosynthetic methods. See,e.g., Ma et al., (1993) Biochemistry, 32:7939; and Hohsaka et al.,(1999) J. Am. Chem. Soc., 121:34. CGGG and AGGU were used tosimultaneously incorporate 2-naphthylalanine and an NBD derivative oflysine into streptavidin in vitro with two chemically acylatedframeshift suppressor tRNAs. See, e.g., Hohsaka et al., (1999) J. Am.Chem. Soc., 121:12194. In an in vivo study, Moore et al. examined theability of tRNALeu derivatives with NCUA anticodons to suppress UAGNcodons (N can be U, A, G, or C), and found that the quadruplet UAGA canbe decoded by a tRNALeu with a UCUA anticodon with an efficiency of 13to 26% with little decoding in the 0 or −1 frame. See, Moore et al.,(2000) J. Mol. Biol., 298:195. In one embodiment, extended codons basedon rare codons or nonsense codons can be used in the present invention,which can reduce missense readthrough and frameshift suppression atother unwanted sites.

For a given system, a selector codon can also include one of the naturalthree base codons, where the endogenous system does not use (or rarelyuses) the natural base codon. For example, this includes a system thatis lacking a tRNA that recognizes the natural three base codon, and/or asystem where the three base codon is a rare codon.

Selector codons optionally include unnatural base pairs. These unnaturalbase pairs further expand the existing genetic alphabet. One extra basepair increases the number of triplet codons from 64 to 125. Propertiesof third base pairs include stable and selective base pairing, efficientenzymatic incorporation into DNA with high fidelity by a polymerase, andthe efficient continued primer extension after synthesis of the nascentunnatural base pair. Descriptions of unnatural base pairs which can beadapted for methods and compositions include, e.g., Hirao, et al.,(2002) An unnatural base pair for incorporating amino acid analoguesinto protein, Nature Biotechnology, 20:177-182. Other relevantpublications are listed below.

For in vivo usage, the unnatural nucleoside is membrane permeable and isphosphorylated to form the corresponding triphosphate. In addition, theincreased genetic information is stable and not destroyed by cellularenzymes. Previous efforts by Benner and others took advantage ofhydrogen bonding patterns that are different from those in canonicalWatson-Crick pairs, the most noteworthy example of which is theiso-C:iso-G pair. See, e.g., Switzer et al., (1989) J. Am. Chem. Soc.,111:8322; and Piccirilli et al., (1990) Nature, 343:33; Kool, (2000)Curr. Opin. Chem. Biol., 4:602. These bases in general mispair to somedegree with natural bases and cannot be enzymatically replicated. Kooland co-workers demonstrated that hydrophobic packing interactionsbetween bases can replace hydrogen bonding to drive the formation ofbase pair. See, Kool, (2000) Curr. Opin. Chem. Biol. 4:602; and Guckianand Kool, (1998) Angew. Chem. Int. Ed. Engl., 36, 2825. In an effort todevelop an unnatural base pair satisfying all the above requirements,Schultz, Romesberg and co-workers have systematically synthesized andstudied a series of unnatural hydrophobic bases. A PICS:PICS self-pairis found to be more stable than natural base pairs, and can beefficiently incorporated into DNA by Klenow fragment of Escherichia coliDNA polymerase I (KF). See, e.g., McMinn et al., (1999) J. Am. Chem.Soc., 121:11586; and Ogawa et al., (2000) J. Am. Chem. Soc., 122:3274. A3MN:3MN self-pair can be synthesized by KF with efficiency andselectivity sufficient for biological function. See, e.g., Ogawa et al.,(2000) J. Am. Chem. Soc. 122:8803. However, both bases act as a chainterminator for further replication. A mutant DNA polymerase has beenrecently evolved that can be used to replicate the PICS self pair. Inaddition, a 7AI self pair can be replicated. See, e.g., Tae et al.,(2001) J. Am. Chem. Soc., 123:7439. A novel metallobase pair, Dipic:Py,has also been developed, which forms a stable pair upon binding Cu(II).See, Meggers et al., (2000) J. Am. Chem. Soc., 122:10714. Becauseextended codons and unnatural codons are intrinsically orthogonal tonatural codons, the methods of the invention can take advantage of thisproperty to generate orthogonal tRNAs for them.

A translational bypassing system can also be used to incorporate anunnatural amino acid in a desired polypeptide. In a translationalbypassing system, a large sequence is incorporated into a gene but isnot translated into protein. The sequence contains a structure thatserves as a cue to induce the ribosome to hop over the sequence andresume translation downstream of the insertion.

In certain embodiments, the protein or polypeptide of interest (orportion thereof) in the methods and/or compositions of the invention isencoded by a nucleic acid. Typically, the nucleic acid comprises atleast one selector codon, at least two selector codons, at least threeselector codons, at least four selector codons, at least five selectorcodons, at least six selector codons, at least seven selector codons, atleast eight selector codons, at least nine selector codons, ten or moreselector codons.

Genes coding for proteins or polypeptides of interest can be mutagenizedusing methods well-known to one of skill in the art and described hereinto include, for example, one or more selector codon for theincorporation of an unnatural amino acid. For example, a nucleic acidfor a protein of interest is mutagenized to include one or more selectorcodon, providing for the incorporation of one or more unnatural aminoacids. The invention includes any such variant, including but notlimited to, mutant, versions of any protein, for example, including atleast one unnatural amino acid. Similarly, the invention also includescorresponding nucleic acids, i.e., any nucleic acid with one or moreselector codon that encodes one or more unnatural amino acid.

Nucleic acid molecules encoding a protein of interest such as a hGHpolypeptide may be readily mutated to introduce a cysteine at anydesired position of the polypeptide. Cysteine is widely used tointroduce reactive molecules, water soluble polymers, proteins, or awide variety of other molecules, onto a protein of interest. Methodssuitable for the incorporation of cysteine into a desired position ofthe hGH polypeptide are well known in the art, such as those describedin U.S. Pat. No. 6,608,183, which is incorporated by reference herein,and standard mutagenesis techniques.

IV. Non-Naturally Encoded Amino Acids

A very wide variety of non-naturally encoded amino acids are suitablefor use in the present invention. Any number of non-naturally encodedamino acids can be introduced into a hGH polypeptide. In general, theintroduced non-naturally encoded amino acids are substantiallychemically inert toward the 20 common, genetically-encoded amino acids(i.e., alanine, arginine, asparagine, aspartic acid, cysteine,glutamine, glutamic acid, glycine, histidine, isoleucine, leucine,lysine, methionine, phenylalanine, proline, serine, threonine,tryptophan, tyrosine, and valine). In some embodiments, thenon-naturally encoded amino acids include side chain functional groupsthat react efficiently and selectively with functional groups not foundin the 20 common amino acids (including but not limited to, azido,ketone, aldehyde and aminooxy groups) to form stable conjugates. Forexample, a hGH polypeptide that includes a non-naturally encoded aminoacid containing an azido functional group can be reacted with a polymer(including but not limited to, poly(ethylene glycol) or, alternatively,a second polypeptide containing an alkyne moiety to form a stableconjugate resulting for the selective reaction of the azide and thealkyne functional groups to form a Huisgen [3+2] cycloaddition product.

The generic structure of an alpha-amino acid is illustrated as follows(Formula I):

A non-naturally encoded amino acid is typically any structure having theabove-listed formula wherein the R group is any substituent other thanone used in the twenty natural amino acids, and may be suitable for usein the present invention. Because the non-naturally encoded amino acidsof the invention typically differ from the natural amino acids only inthe structure of the side chain, the non-naturally encoded amino acidsformamide bonds with other amino acids, including but not limited to,natural or non-naturally encoded, in the same manner in which they areformed in naturally occurring polypeptides. However, the non-naturallyencoded amino acids have side chain groups that distinguish them fromthe natural amino acids. For example, R optionally comprises an alkyl-,aryl-, acyl-, keto-, azido-, hydroxyl-, hydrazine, cyano-, halo-,hydrazide, alkenyl, alkynl, ether, thiol, seleno-, sulfonyl-, borate,boronate, phospho, phosphono, phosphine, heterocyclic, enone, imine,aldehyde, ester, thioacid, hydroxylamine, amino group, or the like orany combination thereof. Other non-naturally occurring amino acids ofinterest that may be suitable for use in the present invention include,but are not limited to, amino acids comprising a photoactivatablecross-linker, spin-labeled amino acids, fluorescent amino acids, metalbinding amino acids, metal-containing amino acids, radioactive aminoacids, amino acids with novel functional groups, amino acids thatcovalently or noncovalently interact with other molecules, photocagedand/or photoisomerizable amino acids, amino acids comprising biotin or abiotin analogue, glycosylated amino acids such as a sugar substitutedserine, other carbohydrate modified amino acids, keto-containing aminoacids, amino acids comprising polyethylene glycol or polyether, heavyatom substituted amino acids, chemically cleavable and/or photocleavableamino acids, amino acids with an elongated side chains as compared tonatural amino acids, including but not limited to, polyethers or longchain hydrocarbons, including but not limited to, greater than about 5or greater than about 10 carbons, carbon-linked sugar-containing aminoacids, redox-active amino acids, amino thioacid containing amino acids,and amino acids comprising one or more toxic moiety.

Exemplary non-naturally encoded amino acids that may be suitable for usein the present invention and that are useful for reactions with watersoluble polymers include, but are not limited to, those with carbonyl,aminooxy, hydrazine, hydrazide, semicarbazide, azide and alkyne reactivegroups. In some embodiments, non-naturally encoded amino acids comprisea saccharide moiety. Examples of such amino acids includeN-acetyl-L-glucosaminyl-L-serine, N-acetyl-L-galactosaminyl-L-serine,N-acetyl-L-glucosaminyl-L-threonine,N-acetyl-L-glucosaminyl-L-asparagine and O-mannosaminyl-L-serine.Examples of such amino acids also include examples where thenaturally-occurring N- or O-linkage between the amino acid and thesaccharide is replaced by a covalent linkage not commonly found innature—including but not limited to, an alkene, an oxime, a thioether,an amide and the like. Examples of such amino acids also includesaccharides that are not commonly found in naturally-occurring proteinssuch as 2-deoxy-glucose, 2-deoxygalactose and the like.

Many of the non-naturally encoded amino acids provided herein arecommercially available, e.g., from Sigma-Aldrich (St. Louis, Mo., USA),Novabiochem (a division of EMD Biosciences, Darmstadt, Germany), orPeptech (Burlington, Mass., USA). Those that are not commerciallyavailable are optionally synthesized as provided herein or usingstandard methods known to those of skill in the art. For organicsynthesis techniques, see, e.g., Organic Chemistry by Fessendon andFessendon, (1982, Second Edition, Willard Grant Press, Boston Mass.);Advanced Organic Chemistry by March (Third Edition, 1985, Wiley andSons, New York); and Advanced Organic Chemistry by Carey and Sundberg(Third Edition, Parts A and B, 1990, Plenum Press, New York). See, also,U.S. Patent Application Publications 2003/0082575 and 2003/0108885,which is incorporated by reference herein. In addition to unnaturalamino acids that contain novel side chains, unnatural amino acids thatmay be suitable for use in the present invention also optionallycomprise modified backbone structures, including but not limited to, asillustrated by the structures of Formula II and III:

wherein Z typically comprises OH, NH₂, SH, NH—R′, or S—R′; X and Y,which can be the same or different, typically comprise S or O, and R andR′, which are optionally the same or different, are typically selectedfrom the same list of constituents for the R group described above forthe unnatural amino acids having Formula I as well as hydrogen. Forexample, unnatural amino acids of the invention optionally comprisesubstitutions in the amino or carboxyl group as illustrated by FormulasII and III. Unnatural amino acids of this type include, but are notlimited to, α-hydroxy acids, α-thioacids, α-aminothiocarboxylates,including but not limited to, with side chains corresponding to thecommon twenty natural amino acids or unnatural side chains. In addition,substitutions at the α-carbon optionally include, but are not limitedto, L, D, or α-α-disubstituted amino acids such as D-glutamate,D-alanine, D-methyl-O-tyrosine, aminobutyric acid, and the like. Otherstructural alternatives include cyclic amino acids, such as prolineanalogues as well as 3, 4, 6, 7, 8, and 9 membered ring prolineanalogues, β and γ amino acids such as substituted β-alanine and γ-aminobutyric acid.

Many unnatural amino acids are based on natural amino acids, such astyrosine, glutamine, phenylalanine, and the like, and are suitable foruse in the present invention. Tyrosine analogs include, but are notlimited to, para-substituted tyrosines, ortho-substituted tyrosines, andmeta substituted tyrosines, where the substituted tyrosine comprises,including but not limited to, a keto group (including but not limitedto, an acetyl group), a benzoyl group, an amino group, a hydrazine, anhydroxyamine, a thiol group, a carboxy group, an isopropyl group, amethyl group, a C₆-C₂₀ straight chain or branched hydrocarbon, asaturated or unsaturated hydrocarbon, an O-methyl group, a polyethergroup, a nitro group, an alkynyl group or the like. In addition,multiply substituted aryl rings are also contemplated. Glutamine analogsthat may be suitable for use in the present invention include, but arenot limited to, α-hydroxy derivatives, γ-substituted derivatives, cyclicderivatives, and amide substituted glutamine derivatives. Examplephenylalanine analogs that may be suitable for use in the presentinvention include, but are not limited to, para-substitutedphenylalanines, ortho-substituted phenyalanines, and meta-substitutedphenylalanines, where the substituent comprises, including but notlimited to, a hydroxy group, a methoxy group, a methyl group, an allylgroup, an aldehyde, an azido, an iodo, a bromo, a keto group (includingbut not limited to, an acetyl group), a benzoyl, an alkynyl group, orthe like. Specific examples of unnatural amino acids that may besuitable for use in the present invention include, but are not limitedto, a p-acetyl-L-phenylalanine, an O-methyl-L-tyrosine, anL-3-(2-naphthyl)alanine, a 3-methyl-phenylalanine, anO-4-allyl-L-tyrosine, a 4-propyl-L-tyrosine, atri-O-acetyl-GlcNAcβ-serine, an L-Dopa, a fluorinated phenylalanine, anisopropyl-L-phenylalanine, a p-azido-L-phenylalanine, ap-acyl-L-phenylalanine, a p-benzoyl-L-phenylalanine, an L-phosphoserine,a phosphonoserine, a phosphonotyrosine, a p-iodo-phenylalanine, ap-bromophenylalanine, a p-amino-L-phenylalanine, anisopropyl-L-phenylalanine, and a p-propargyloxy-phenylalanine, and thelike. Examples of structures of a variety of unnatural amino acids thatmay be suitable for use in the present invention are provided in, forexample, WO 2002/085923 entitled “In vivo incorporation of unnaturalamino acids.” See also Kiick et al., (2002) Incorporation of azides intorecombinant proteins for chemoselective modification by the Staudingerligation, PNAS 99:19-24, for additional methionine analogs.

In one embodiment, compositions of a hGH polypeptide that include anunnatural amino acid (such as p-(propargyloxy)-phenyalanine) areprovided. Various compositions comprising p-(propargyloxy)-phenyalanineand, including but not limited to, proteins and/or cells, are alsoprovided. In one aspect, a composition that includes thep-(propargyloxy)-phenyalanine unnatural amino acid, further includes anorthogonal tRNA. The unnatural amino acid can be bonded (including butnot limited to, covalently) to the orthogonal tRNA, including but notlimited to, covalently bonded to the orthogonal tRNA though anamino-acyl bond, covalently bonded to a 3′OH or a 2′OH of a terminalribose sugar of the orthogonal tRNA, etc.

The chemical moieties via unnatural amino acids that can be incorporatedinto proteins offer a variety of advantages and manipulations of theprotein. For example, the unique reactivity of a keto functional groupallows selective modification of proteins with any of a number ofhydrazine- or hydroxylamine-containing reagents in vitro and in vivo. Aheavy atom unnatural amino acid, for example, can be useful for phasingX-ray structure data. The site-specific introduction of heavy atomsusing unnatural amino acids also provides selectivity and flexibility inchoosing positions for heavy atoms. Photoreactive unnatural amino acids(including but not limited to, amino acids with benzophenone andarylazides (including but not limited to, phenylazide) side chains), forexample, allow for efficient in vivo and in vitro photocrosslinking ofprotein. Examples of photoreactive unnatural amino acids include, butare not limited to, p-azido-phenylalanine and p-benzoyl-phenylalanine.The protein with the photoreactive unnatural amino acids can then becrosslinked at will by excitation of the photoreactive group-providingtemporal control. In one example, the methyl group of an unnatural aminocan be substituted with an isotopically labeled, including but notlimited to, methyl group, as a probe of local structure and dynamics,including but not limited to, with the use of nuclear magnetic resonanceand vibrational spectroscopy. Alkynyl or azido functional groups, forexample, allow the selective modification of proteins with moleculesthrough a [3+2] cycloaddition reaction.

A non-natural amino acid incorporated into a polypeptide at the aminoterminus can be composed of an R group that is any substituent otherthan one used in the twenty natural amino acids and a 2^(nd) reactivegroup different from the NH₂ group normally present in α-amino acids(see Formula I). A similar non-natural amino acid can be incorporated atthe carboxyl terminus with a 2^(nd) reactive group different from theCOOH group normally present in α-amino acids (see Formula I).

Chemical Synthesis of Unnatural Amino Acids

Many of the unnatural amino acids suitable for use in the presentinvention are commercially available, e.g., from Sigma (USA) or Aldrich(Milwaukee, Wis., USA). Those that are not commercially available areoptionally synthesized as provided herein or as provided in variouspublications or using standard methods known to those of skill in theart. For organic synthesis techniques, see, e.g., Organic Chemistry byFessendon and Fessendon, (1982, Second Edition, Willard Grant Press,Boston Mass.); Advanced Organic Chemistry by March (Third Edition, 1985,Wiley and Sons, New York); and Advanced Organic Chemistry by Carey andSundberg (Third Edition, Parts A and B, 1990, Plenum Press, New York).Additional publications describing the synthesis of unnatural aminoacids include, e.g., WO 2002/085923 entitled “In vivo incorporation ofUnnatural Amino Acids;” Matsoukas et al., (1995) J. Med. Chem., 38,4660-4669; King, F. E. & Kidd, D. A. A. (1949) A New Synthesis ofGlutamine and of γ-Dipeptides of Glutamic Acid from PhthylatedIntermediates. J. Chem. Soc, 3315-3319; Friedman, O. M. & Chatterrji, R.(1959) Synthesis of Derivatives of Glutamine as Model Substrates forAnti-Tumor Agents. J. Am. Chem. Soc. 81, 3750-3752; Craig, J. C. et al.(1988) Absolute Configuration of the Enantiomers of 7-Chloro-4[[4-(diethylamino)-1-methylbutyl]amino]quinoline (Chloroquine). J. Org.Chem. 53, 1167-1170; Azoulay, M., Vilmont, M. & Frappier, F. (1991)Glutamine analogues as Potential Antimalarials, Eur. J. Med. Chem. 26,201-5; Koskinen, A. M. P. & Rapoport, H. (1989) Synthesis of4-Substituted Prolines as Conformationally Constrained Amino AcidAnalogues. J. Org. Chem. 54, 1859-1866; Christie, B. D. & Rapoport, H.(1985) Synthesis of Optically Pure Pipecolates from L-Asparagine.Application to the Total Synthesis of (+)-Apovincamine through AminoAcid Decarbonylation and Iminium Ion Cyclization. J. Org. Chem.1989:1859-1866; Barton et al., (1987) Synthesis of Novel α-Amino-Acidsand Derivatives Using Radical Chemistry: Synthesis of L-andD-a-Amino-Adipic Acids, L-a-aminopimelic Acid and AppropriateUnsaturated Derivatives. Tetrahedron Lett. 43:4297-4308; and, Subasingheet al., (1992) Quisqualic acid analogues: synthesis of beta-heterocyclic2-aminopropanoic acid derivatives and their activity at a novelquisqualate-sensitized site. J. Med. Chem. 35:4602-7. See also, patentapplications entitled “Protein Arrays,” filed Dec. 22, 2003, Ser. No.10/744,899 and Ser. No. 60/435,821 filed on Dec. 22, 2002.

A. Carbonyl Reactive Groups

Amino acids with a carbonyl reactive group allow for a variety ofreactions to link molecules (including but not limited to, PEG or otherwater soluble molecules) via nucleophilic addition or aldol condensationreactions among others.

Exemplary carbonyl-containing amino acids can be represented as follows:

wherein n is 0-10; R₁ is an alkyl, aryl, substituted alkyl, orsubstituted aryl; R₂ is H, alkyl, aryl, substituted alkyl, andsubstituted aryl; and R₃ is H, an amino acid, a polypeptide, or an aminoterminus modification group, and R₄ is H, an amino acid, a polypeptide,or a carboxy terminus modification group. In some embodiments, n is 1,R₁ is phenyl and R₂ is a simple alkyl (i.e., methyl, ethyl, or propyl)and the ketone moiety is positioned in the para position relative to thealkyl side chain. In some embodiments, n is 1, R₁ is phenyl and R₂ is asimple alkyl (i.e., methyl, ethyl, or propyl) and the ketone moiety ispositioned in the meta position relative to the alkyl side chain.

The synthesis of p-acetyl-(+/−)-phenylalanine andm-acetyl-(+/−)-phenylalanine is described in Zhang, Z., et al.,Biochemistry 42: 6735-6746 (2003), which is incorporated by referenceherein. Other carbonyl-containing amino acids can be similarly preparedby one skilled in the art.

In some embodiments, a polypeptide comprising a non-naturally encodedamino acid is chemically modified to generate a reactive carbonylfunctional group. For instance, an aldehyde functionality useful forconjugation reactions can be generated from a functionality havingadjacent amino and hydroxyl groups. Where the biologically activemolecule is a polypeptide, for example, an N-terminal serine orthreonine (which may be normally present or may be exposed via chemicalor enzymatic digestion) can be used to generate an aldehydefunctionality under mild oxidative cleavage conditions using periodate.See, e.g., Gaertner, et al., Bioconjug. Chem. 3: 262-268 (1992);Geoghegan, K. & Stroh, J., Bioconjug. Chem. 3:138-146 (1992); Gaertneret al., J. Biol. Chem. 269:7224-7230 (1994). However, methods known inthe art are restricted to the amino acid at the N-terminus of thepeptide or protein.

In the present invention, a non-naturally encoded amino acid bearingadjacent hydroxyl and amino groups can be incorporated into thepolypeptide as a “masked” aldehyde functionality. For example,5-hydroxylysine bears a hydroxyl group adjacent to the epsilon amine.Reaction conditions for generating the aldehyde typically involveaddition of molar excess of sodium metaperiodate under mild conditionsto avoid oxidation at other sites within the polypeptide. The pH of theoxidation reaction is typically about 7.0. A typical reaction involvesthe addition of about 1.5 molar excess of sodium meta periodate to abuffered solution of the polypeptide, followed by incubation for about10 minutes in the dark. See, e.g. U.S. Pat. No. 6,423,685, which isincorporated by reference herein.

The carbonyl functionality can be reacted selectively with a hydrazine-,hydrazide-, hydroxylamine-, or semicarbazide-containing reagent undermild conditions in aqueous solution to form the corresponding hydrazone,oxime, or semicarbazone linkages, respectively, that are stable underphysiological conditions. See, e.g., Jencks, W. P., J. Am. Chem. Soc.81, 475-481 (1959); Shao, J. and Tam, J. P., J. Am. Chem. Soc.117:3893-3899 (1995). Moreover, the unique reactivity of the carbonylgroup allows for selective modification in the presence of the otheramino acid side chains. See, e.g., Cornish, V. W., et al., J. Am. Chem.Soc. 118:8150-8151 (1996); Geoghegan, K. F. & Stroh, J. G., Bioconjug.Chem. 3:138-146 (1992); Mahal, L. K., et al., Science 276:1125-1128(1997).

B. Hydrazine, Hydrazide or Semicarbazide Reactive Groups

Non-naturally encoded amino acids containing a nucleophilic group, suchas a hydrazine, hydrazide or semicarbazide, allow for reaction with avariety of electrophilic groups to form conjugates (including but notlimited to, with PEG or other water soluble polymers).

Exemplary hydrazine, hydrazide or semicarbazide-containing amino acidscan be represented as follows:

wherein n is 0-10; R₁ is an alkyl, aryl, substituted alkyl, orsubstituted aryl or not present; X, is O, N, or S or not present; R₂ isH, an amino acid, a polypeptide, or an amino terminus modificationgroup, and R₃ is H, an amino acid, a polypeptide, or a carboxy terminusmodification group.

In some embodiments, n is 4, R₁ is not present, and X is N. In someembodiments, n is 2, R₁ is not present, and X is not present. In someembodiments, n is 1, R₁ is phenyl, X is O, and the oxygen atom ispositioned para to the aliphatic group on the aryl ring.

Hydrazide-, hydrazine-, and semicarbazide-containing amino acids areavailable from commercial sources. For instance, L-glutamate-γ-hydrazideis available from Sigma Chemical (St. Louis, Mo.). Other amino acids notavailable commercially can be prepared by one skilled in the art. See,e.g., U.S. Pat. No. 6,281,211, which is incorporated by referenceherein.

Polypeptides containing non-naturally encoded amino acids that bearhydrazide, hydrazine or semicarbazide functionalities can be reactedefficiently and selectively with a variety of molecules that containaldehydes or other functional groups with similar chemical reactivity.See, e.g., Shao, J. and Tam, J., J. Am. Chem. Soc. 117:3893-3899 (1995).The unique reactivity of hydrazide, hydrazine and semicarbazidefunctional groups makes them significantly more reactive towardaldehydes, ketones and other electrophilic groups as compared to thenucleophilic groups present on the 20 common amino acids (including butnot limited to, the hydroxyl group of serine or threonine or the aminogroups of lysine and the N-terminus).

C. Aminooxy-Containing Amino Acids

Non-naturally encoded amino acids containing an aminooxy (also called ahydroxylamine) group allow for reaction with a variety of electrophilicgroups to form conjugates (including but not limited to, with PEG orother water soluble polymers). Like hydrazines, hydrazides andsemicarbazides, the enhanced nucleophilicity of the aminooxy grouppermits it to react efficiently and selectively with a variety ofmolecules that contain aldehydes or other functional groups with similarchemical reactivity. See, e.g., Shao, J. and Tam, J., J. Am. Chem. Soc.117:3893-3899 (1995); H. Hang and C. Bertozzi, Acc. Chem. Res. 34:727-736 (2001). Whereas the result of reaction with a hydrazine group isthe corresponding hydrazone, however, an oxime results generally fromthe reaction of an aminooxy group with a carbonyl-containing group suchas a ketone.

Exemplary amino acids containing aminooxy groups can be represented asfollows:

wherein n is 0-10; R₁ is an alkyl, aryl, substituted alkyl, orsubstituted aryl or not present; X is O, N, S or not present; m is 0-10;Y=C(O) or not present; R₂ is H, an amino acid, a polypeptide, or anamino terminus modification group, and R₃ is H, an amino acid, apolypeptide, or a carboxy terminus modification group. In someembodiments, n is 1, R₁ is phenyl, X is O, m is 1, and Y is present. Insome embodiments, n is 2, R₁ and X are not present, m is 0, and Y is notpresent.

Aminooxy-containing amino acids can be prepared from readily availableamino acid precursors (homoserine, serine and threonine). See, e.g., M.Carrasco and R. Brown, J. Org. Chem. 68: 8853-8858 (2003). Certainaminooxy-containing amino acids, such as L-2-amino-4-(aminooxy)butyricacid), have been isolated from natural sources (Rosenthal, G. et al.,Life Sci. 60: 1635-1641 (1997). Other aminooxy-containing amino acidscan be prepared by one skilled in the art.

D. Azide and Alkyne Reactive Groups

The unique reactivity of azide and alkyne functional groups makes themextremely useful for the selective modification of polypeptides andother biological molecules. Organic azides, particularly aliphaticazides, and alkynes are generally stable toward common reactive chemicalconditions. In particular, both the azide and the alkyne functionalgroups are inert toward the side chains (i.e., R groups) of the 20common amino acids found in naturally-occurring polypeptides. Whenbrought into close proximity, however, the “spring-loaded” nature of theazide and alkyne groups is revealed and they react selectively andefficiently via Huisgen [3+2] cycloaddition reaction to generate thecorresponding triazole. See, e.g., Chin J., et al., Science 301:964-7(2003); Wang, Q., et al., J. Am. Chem. Soc. 125, 3192-3193 (2003); Chin,J. W., et al., J. Am. Chem. Soc. 124:9026-9027 (2002).

Because the Huisgen cycloaddition reaction involves a selectivecycloaddition reaction (see, e.g., Padwa, A., in COMPREHENSIVE ORGANICSYNTHESIS, Vol. 4, (ed. Trost, B. M., 1991), p. 1069-1109; Huisgen, R.in 1,3-DIPOLAR CYCLOADDITION CHEMISTRY, (ed. Padwa, A., 1984), p. 1-176)rather than a nucleophilic substitution, the incorporation ofnon-naturally encoded amino acids bearing azide and alkyne-containingside chains permits the resultant polypeptides to be modifiedselectively at the position of the non-naturally encoded amino acid.Cycloaddition reaction involving azide or alkyne-containing hGHpolypeptide can be carried out at room temperature under aqueousconditions by the addition of Cu(II) (including but not limited to, inthe form of a catalytic amount of CuSO₄) in the presence of a reducingagent for reducing Cu(II) to Cu(I), in situ, in catalytic amount. See,e.g., Wang, Q., et al., J. Am. Chem. Soc. 125, 3192-3193 (2003); Tornoe,C. W., et al., J. Org. Chem. 67:3057-3064 (2002); Rostovtsev, et al.,Angew. Chem. Int. Ed. 41:2596-2599 (2002). Exemplary reducing agentsinclude, including but not limited to, ascorbate, metallic copper,quinine, hydroquinone, vitamin K, glutathione, cysteine, Fe²⁺, Co²⁺, andan applied electric potential.

In some cases, where a Huisgen [3+2] cycloaddition reaction between anazide and an alkyne is desired, the hGH polypeptide comprises anon-naturally encoded amino acid comprising an alkyne moiety and thewater soluble polymer to be attached to the amino acid comprises anazide moiety. Alternatively, the converse reaction (i.e., with the azidemoiety on the amino acid and the alkyne moiety present on the watersoluble polymer) can also be performed.

The azide functional group can also be reacted selectively with a watersoluble polymer containing an aryl ester and appropriatelyfunctionalized with an aryl phosphine moiety to generate an amidelinkage. The aryl phosphine group reduces the azide in situ and theresulting amine then reacts efficiently with a proximal ester linkage togenerate the corresponding amide. See, e.g., E. Saxon and C. Bertozzi,Science 287, 2007-2010 (2000). The azide-containing amino acid can beeither an alkyl azide (including but not limited to,2-amino-6-azido-1-hexanoic acid) or an aryl azide(p-azido-phenylalanine).

Exemplary water soluble polymers containing an aryl ester and aphosphine moiety can be represented as follows:

wherein X can be O, N, S or not present, Ph is phenyl, W is a watersoluble polymer and R can be H, alkyl, aryl, substituted alkyl andsubstituted aryl groups. Exemplary R groups include but are not limitedto —CH₂, —C(CH₃)₃, —OR′, —NR′R″, —SR′, -halogen, —C(O)R′, —CONR′R″,—S(O)₂R′, —S(O)₂NR′R″, —CN and —NO₂. R′, R″, R′″ and R″″ eachindependently refer to hydrogen, substituted or unsubstitutedheteroalkyl, substituted or unsubstituted aryl, including but notlimited to, aryl substituted with 1-3 halogens, substituted orunsubstituted alkyl, alkoxy or thioalkoxy groups, or arylalkyl groups.When a compound of the invention includes more than one R group, forexample, each of the R groups is independently selected as are each R′,R″, R′″ and R″″ groups when more than one of these groups is present.When R′ and R″ are attached to the same nitrogen atom, they can becombined with the nitrogen atom to form a 5-, 6-, or 7-membered ring.For example, —NR′R″ is meant to include, but not be limited to,1-pyrrolidinyl and 4-morpholinyl. From the above discussion ofsubstituents, one of skill in the art will understand that the term“alkyl” is meant to include groups including carbon atoms bound togroups other than hydrogen groups, such as haloalkyl (including but notlimited to, —CF₃ and —CH₂CF₃) and acyl (including but not limited to,—C(O)CH₃, —C(O)CF₃, —C(O)CH₂OCH₃, and the like).

The azide functional group can also be reacted selectively with a watersoluble polymer containing a thioester and appropriately functionalizedwith an aryl phosphine moiety to generate an amide linkage. The arylphosphine group reduces the azide in situ and the resulting amine thenreacts efficiently with the thioester linkage to generate thecorresponding amide. Exemplary water soluble polymers containing athioester and a phosphine moiety can be represented as follows:

wherein n is 1-10; X can be O, N, S or not present, Ph is phenyl, and Wis a water soluble polymer.

Exemplary alkyne-containing amino acids can be represented as follows:

wherein n is 0-10; R₁ is an alkyl, aryl, substituted alkyl, orsubstituted aryl or not present; X is O, N, S or not present; m is 0-10,R₂ is H, an amino acid, a polypeptide, or an amino terminus modificationgroup, and R₃ is H, an amino acid, a polypeptide, or a carboxy terminusmodification group. In some embodiments, n is 1, R₁ is phenyl, X is notpresent, m is 0 and the acetylene moiety is positioned in the paraposition relative to the alkyl side chain. In some embodiments, n is 1,R₁ is phenyl, X is O, m is 1 and the propargyloxy group is positioned inthe para position relative to the alkyl side chain (i.e.,O-propargyl-tyrosine). In some embodiments, n is 1, R₁ and X are notpresent and m is 0 (i.e., proparylglycine).

Alkyne-containing amino acids are commercially available. For example,propargylglycine is commercially available from Peptech (Burlington,Mass.). Alternatively, alkyne-containing amino acids can be preparedaccording to standard methods. For instance, p-propargyloxyphenylalaninecan be synthesized, for example, as described in Deiters, A., et al., J.Am. Chem. Soc. 125: 11782-11783 (2003), and 4-alkynyl-L-phenylalaninecan be synthesized as described in Kayser, B., et al., Tetrahedron53(7): 2475-2484 (1997). Other alkyne-containing amino acids can beprepared by one skilled in the art.

Exemplary azide-containing amino acids can be represented as follows:

wherein n is 0-10; R₁ is an alkyl, aryl, substituted alkyl, substitutedaryl or not present; X is O, N, S or not present; m is 0-10; R₂ is H, anamino acid, a polypeptide, or an amino terminus modification group, andR₃ is H, an amino acid, a polypeptide, or a carboxy terminusmodification group. In some embodiments, n is 1, R₁ is phenyl, X is notpresent, m is 0 and the azide moiety is positioned para to the alkylside chain. In some embodiments, n is 0-4 and R₁ and X are not present,and m=0. In some embodiments, n is 1, R₁ is phenyl, X is O, m is 2 andthe β-azidoethoxy moiety is positioned in the para position relative tothe alkyl side chain.

Azide-containing amino acids are available from commercial sources. Forinstance, 4-azidophenylalanine can be obtained from Chem-ImpexInternational, Inc. (Wood Dale, Ill.). For those azide-containing aminoacids that are not commercially available, the azide group can beprepared relatively readily using standard methods known to those ofskill in the art, including but not limited to, via displacement of asuitable leaving group (including but not limited to, halide, mesylate,tosylate) or via opening of a suitably protected lactone. See, e.g.,Advanced Organic Chemistry by March (Third Edition, 1985, Wiley andSons, New York).

E. Aminothiol Reactive Groups

The unique reactivity of beta-substituted aminothiol functional groupsmakes them extremely useful for the selective modification ofpolypeptides and other biological molecules that contain aldehyde groupsvia formation of the thiazolidine. See, e.g., J. Shao and J. Tam, J. Am.Chem. Soc. 1995, 117 (14) 3893-3899. In some embodiments,beta-substituted aminothiol amino acids can be incorporated into hGHpolypeptides and then reacted with water soluble polymers comprising analdehyde functionality. In some embodiments, a water soluble polymer,drug conjugate or other payload can be coupled to a hGH polypeptidecomprising a beta-substituted aminothiol amino acid via formation of thethiazolidine.

Cellular Uptake of Unnatural Amino Acids

Unnatural amino acid uptake by a eukaryotic cell is one issue that istypically considered when designing and selecting unnatural amino acids,including but not limited to, for incorporation into a protein. Forexample, the high charge density of α-amino acids suggests that thesecompounds are unlikely to be cell permeable. Natural amino acids aretaken up into the eukaryotic cell via a collection of protein-basedtransport systems. A rapid screen can be done which assesses whichunnatural amino acids, if any, are taken up by cells. See, e.g., thetoxicity assays in, e.g., the applications entitled “Protein Arrays,”filed Dec. 22, 2003, Ser. No. 10/744,899 and Ser. No. 60/435,821 filedon Dec. 22, 2002; and Liu, D. R. & Schultz, P. G. (1999) Progress towardthe evolution of an organism with an expanded genetic code. PNAS UnitedStates 96:4780-4785. Although uptake is easily analyzed with variousassays, an alternative to designing unnatural amino acids that areamenable to cellular uptake pathways is to provide biosynthetic pathwaysto create amino acids in vivo.

Biosynthesis of Unnatural Amino Acids

Many biosynthetic pathways already exist in cells for the production ofamino acids and other compounds. While a biosynthetic method for aparticular unnatural amino acid may not exist in nature, including butnot limited to, in a eukaryotic cell, the invention provides suchmethods. For example, biosynthetic pathways for unnatural amino acidsare optionally generated in host cell by adding new enzymes or modifyingexisting host cell pathways. Additional new enzymes are optionallynaturally occurring enzymes or artificially evolved enzymes. Forexample, the biosynthesis of p-aminophenylalanine (as presented in anexample in WO 2002/085923 entitled “In vivo incorporation of unnaturalamino acids”) relies on the addition of a combination of known enzymesfrom other organisms. The genes for these enzymes can be introduced intoa eukaryotic cell by transforming the cell with a plasmid comprising thegenes. The genes, when expressed in the cell, provide an enzymaticpathway to synthesize the desired compound. Examples of the types ofenzymes that are optionally added are provided in the examples below.Additional enzymes sequences are found, for example, in Genbank.Artificially evolved enzymes are also optionally added into a cell inthe same manner. In this manner, the cellular machinery and resources ofa cell are manipulated to produce unnatural amino acids.

A variety of methods are available for producing novel enzymes for usein biosynthetic pathways or for evolution of existing pathways. Forexample, recursive recombination, including but not limited to, asdeveloped by Maxygen, Inc. (available on the World Wide Web atmaxygen.com), is optionally used to develop novel enzymes and pathways.See, e.g., Stemmer (1994), Rapid evolution of a protein in vitro by DNAshuffling, Nature 370(4):389-391; and, Stemmer, (1994), DNA shuffling byrandom fragmentation and reassembly: In vitro recombination formolecular evolution, Proc. Natl. Acad. Sci. USA., 91:10747-10751.Similarly DesignPath™, developed by Genencor (available on the WorldWide Web at genencor.com) is optionally used for metabolic pathwayengineering, including but not limited to, to engineer a pathway tocreate O-methyl-L-tyrosine in a cell. This technology reconstructsexisting pathways in host organisms using a combination of new genes,including but not limited to, identified through functional genomics,and molecular evolution and design. Diversa Corporation (available onthe World Wide Web at diversa.com) also provides technology for rapidlyscreening libraries of genes and gene pathways, including but notlimited to, to create new pathways.

Typically, the unnatural amino acid produced with an engineeredbiosynthetic pathway of the invention is produced in a concentrationsufficient for efficient protein biosynthesis, including but not limitedto, a natural cellular amount, but not to such a degree as to affect theconcentration of the other amino acids or exhaust cellular resources.Typical concentrations produced in vivo in this manner are about 10 mMto about 0.05 mM. Once a cell is transformed with a plasmid comprisingthe genes used to produce enzymes desired for a specific pathway and anunnatural amino acid is generated, in vivo selections are optionallyused to further optimize the production of the unnatural amino acid forboth ribosomal protein synthesis and cell growth.

Polypeptides with Unnatural Amino Acids

The incorporation of an unnatural amino acid can be done for a varietyof purposes, including but not limited to, tailoring changes in proteinstructure and/or function, changing size, acidity, nucleophilicity,hydrogen bonding, hydrophobicity, accessibility of protease targetsites, targeting to a moiety (including but not limited to, for aprotein array), etc. Proteins that include an unnatural amino acid canhave enhanced or even entirely new catalytic or biophysical properties.For example, the following properties are optionally modified byinclusion of an unnatural amino acid into a protein: toxicity,biodistribution, structural properties, spectroscopic properties,chemical and/or photochemical properties, catalytic ability, half-life(including but not limited to, serum half-life), ability to react withother molecules, including but not limited to, covalently ornoncovalently, and the like. The compositions including proteins thatinclude at least one unnatural amino acid are useful for, including butnot limited to, novel therapeutics, diagnostics, catalytic enzymes,industrial enzymes, binding proteins (including but not limited to,antibodies), and including but not limited to, the study of proteinstructure and function. See, e.g., Dougherty, (2000) Unnatural AminoAcids as Probes of Protein Structure and Function, Current Opinion inChemical Biology, 4:645-652.

In one aspect of the invention, a composition includes at least oneprotein with at least one, including but not limited to, at least two,at least three, at least four, at least five, at least six, at leastseven, at least eight, at least nine, or at least ten or more unnaturalamino acids. The unnatural amino acids can be the same or different,including but not limited to, there can be 1, 2, 3, 4, 5, 6, 7, 8, 9, or10 or more different sites in the protein that comprise 1, 2, 3, 4, 5,6, 7, 8, 9, or 10 or more different unnatural amino acids. In anotheraspect, a composition includes a protein with at least one, but fewerthan all, of a particular amino acid present in the protein issubstituted with the unnatural amino acid. For a given protein with morethan one unnatural amino acids, the unnatural amino acids can beidentical or different (including but not limited to, the protein caninclude two or more different types of unnatural amino acids, or caninclude two of the same unnatural amino acid). For a given protein withmore than two unnatural amino acids, the unnatural amino acids can bethe same, different or a combination of a multiple unnatural amino acidof the same kind with at least one different unnatural amino acid.

Proteins or polypeptides of interest with at least one unnatural aminoacid are a feature of the invention. The invention also includespolypeptides or proteins with at least one unnatural amino acid producedusing the compositions and methods of the invention. An excipient(including but not limited to, a pharmaceutically acceptable excipient)can also be present with the protein.

By producing proteins or polypeptides of interest with at least oneunnatural amino acid in eukaryotic cells, proteins or polypeptides willtypically include eukaryotic post-translational modifications. Incertain embodiments, a protein includes at least one unnatural aminoacid and at least one post-translational modification that is made invivo by a eukaryotic cell, where the post-translational modification isnot made by a prokaryotic cell. For example, the post-translationmodification includes, including but not limited to, acetylation,acylation, lipid-modification, palmitoylation, palmitate addition,phosphorylation, glycolipid-linkage modification, glycosylation, and thelike. In one aspect, the post-translational modification includesattachment of an oligosaccharide (including but not limited to,(GlcNAc-Man)₂-Man-GlcNAc-GlcNAc)) to an asparagine by aGlcNAc-asparagine linkage. See Table 1 which lists some examples ofN-linked oligosaccharides of eukaryotic proteins (additional residuescan also be present, which are not shown). In another aspect, thepost-translational modification includes attachment of anoligosaccharide (including but not limited to, Gal-GalNAc, Gal-GlcNAc,etc.) to a serine or threonine by a GalNAc-serine or GalNAc-threoninelinkage, or a GlcNAc-serine or a GlcNAc-threonine linkage. TABLE 1EXAMPLES OF OLIGOSACCHARIDES THROUGH GlcNAc-LINKAGE Type Base StructureHigh-mannose

Hybrid

Complex

Xylose

In yet another aspect, the post-translation modification includesproteolytic processing of precursors (including but not limited to,calcitonin precursor, calcitonin gene-related peptide precursor,preproparathyroid hormone, preproinsulin, proinsulin,prepro-opiomelanocortin, pro-opiomelanocortin and the like), assemblyinto a multisubunit protein or macromolecular assembly, translation toanother site in the cell (including but not limited to, to organelles,such as the endoplasmic reticulum, the Golgi apparatus, the nucleus,lysosomes, peroxisomes, mitochondria, chloroplasts, vacuoles, etc., orthrough the secretory pathway). In certain embodiments, the proteincomprises a secretion or localization sequence, an epitope tag, a FLAGtag, a polyhistidine tag, a GST fusion, or the like. U.S. Pat. Nos.4,963,495 and 6,436,674, which are incorporated herein by reference,detail constructs designed to improve secretion of hGH polypeptides.

One advantage of an unnatural amino acid is that it presents additionalchemical moieties that can be used to add additional molecules. Thesemodifications can be made in vivo in a eukaryotic or non-eukaryoticcell, or in vitro. Thus, in certain embodiments, the post-translationalmodification is through the unnatural amino acid. For example, thepost-translational modification can be through anucleophilic-electrophilic reaction. Most reactions currently used forthe selective modification of proteins involve covalent bond formationbetween nucleophilic and electrophilic reaction partners, including butnot limited to the reaction of α-haloketones with histidine or cysteineside chains. Selectivity in these cases is determined by the number andaccessibility of the nucleophilic residues in the protein. In proteinsof the invention, other more selective reactions can be used such as thereaction of an unnatural keto-amino acid with hydrazides or aminooxycompounds, in vitro and in vivo. See, e.g., Cornish, et al., (1996) Am.Chem. Soc., 118:8150-8151; Mahal, et al., (1997) Science, 276:1125-1128;Wang, et al., (2001) Science 292:498-500; Chin, et al., (2002) Am. Chem.Soc. 124:9026-9027; Chin, et al., (2002) Proc. Natl. Acad. Sci.,99:11020-11024; Wang, et al., (2003) Proc. Natl. Acad. Sci., 100:56-61;Zhang, et al., (2003) Biochemistry, 42:6735-6746; and, Chin, et al.,(2003) Science, in press. This allows the selective labeling ofvirtually any protein with a host of reagents including fluorophores,crosslinking agents, saccharide derivatives and cytotoxic molecules. Seealso, U.S. patent application Ser. No. 10/686,944 entitled “Glycoproteinsynthesis” filed Jan. 16, 2003, which is incorporated by referenceherein. Post-translational modifications, including but not limited to,through an azido amino acid, can also made through the Staudingerligation (including but not limited to, with triarylphosphine reagents).See, e.g., Kiick et al., (2002) Incorporation of azides into recombinantproteins for chemoselective modification by the Staudinger ligation,PNAS 99:19-24.

This invention provides another highly efficient method for theselective modification of proteins, which involves the geneticincorporation of unnatural amino acids, including but not limited to,containing an azide or alkynyl moiety into proteins in response to aselector codon. These amino acid side chains can then be modified by,including but not limited to, a Huisgen [3+2] cycloaddition reaction(see, e.g., Padwa, A. in Comprehensive Organic Synthesis, Vol. 4, (1991)Ed. Trost, B. M., Pergamon, Oxford, p. 1069-1109; and, Huisgen, R. in1,3-Dipolar Cycloaddition Chemistry, (1984) Ed. Padwa, A., Wiley, NewYork, p. 1-176) with, including but not limited to, alkynyl or azidederivatives, respectively. Because this method involves a cycloadditionrather than a nucleophilic substitution, proteins can be modified withextremely high selectivity. This reaction can be carried out at roomtemperature in aqueous conditions with excellent regioselectivity(1.4>1.5) by the addition of catalytic amounts of Cu(I) salts to thereaction mixture. See, e.g., Tornoe, et al., (2002) Org. Chem.67:3057-3064; and, Rostovtsev, et al., (2002) Angew. Chem. Int. Ed.41:2596-2599. Another method that can be used is the ligand exchange ona bisarsenic compound with a tetracysteine motif, see, e.g., Griffin, etal., (1998) Science 281:269-272.

A molecule that can be added to a protein of the invention through a[3+2] cycloaddition includes virtually any molecule with an azide oralkynyl derivative. Molecules include, but are not limited to, dyes,fluorophores, crosslinking agents, saccharide derivatives, polymers(including but not limited to, derivatives of polyethylene glycol),photocrosslinkers, cytotoxic compounds, affinity labels, derivatives ofbiotin, resins, beads, a second protein or polypeptide (or more),polynucleotide(s) (including but not limited to, DNA, RNA, etc.), metalchelators, cofactors, fatty acids, carbohydrates, and the like. Thesemolecules can be added to an unnatural amino acid with an alkynyl group,including but not limited to, p-propargyloxyphenylalanine, or azidogroup, including but not limited to, p-azido-phenylalanine,respectively.

V. In Vivo Generation of hGH Polypeptides ComprisingNon-Genetically-Encoded Amino Acids

The hGH polypeptides of the invention can be generated in vivo usingmodified tRNA and tRNA synthetases to add to or substitute amino acidsthat are not encoded in naturally-occurring systems.

Methods for generating tRNAs and tRNA synthetases which use amino acidsthat are not encoded in naturally-occurring systems are described in,e.g., U.S. Patent Application Publications 2003/0082575 (Ser. No.10/126,927) and 2003/0108885 (Ser. No. 10/126,931) which areincorporated by reference herein. These methods involve generating atranslational machinery that functions independently of the synthetasesand tRNAs endogenous to the translation system (and are thereforesometimes referred to as “orthogonal”). Typically, the translationsystem comprises an orthogonal tRNA (O-tRNA) and an orthogonal aminoacyltRNA synthetase (O-RS). Typically, the O-RS preferentially aminoacylatesthe O-tRNA with at least one non-naturally occurring amino acid in thetranslation system and the O-tRNA recognizes at least one selector codonthat is not recognized by other tRNAs in the system. The translationsystem thus inserts the non-naturally-encoded amino acid into a proteinproduced in the system, in response to an encoded selector codon,thereby “substituting” an amino acid into a position in the encodedpolypeptide.

A wide variety of orthogonal tRNAs and aminoacyl tRNA synthetases havebeen described in the art for inserting particular synthetic amino acidsinto polypeptides, and are generally suitable for use in the presentinvention. For example, keto-specific O-tRNA/aminoacyl-tRNA synthetasesare described in Wang, L., et al., Proc. Natl. Acad. Sci. USA 100:56-61(2003) and Zhang, Z. et al., Biochem. 42(22):6735-6746 (2003). ExemplaryO-RS, or portions thereof, are encoded by polynucleotide sequences andinclude amino acid sequences disclosed in U.S. Patent ApplicationPublications 2003/0082575 and 2003/0108885, each incorporated herein byreference. Corresponding O-tRNA molecules for use with the O-RSs arealso described in U.S. Patent Application Publications 2003/0082575(Ser. No. 10/126,927) and 2003/0108885 (Ser. No. 10/126,931) which areincorporated by reference herein.

An example of an azide-specific O-tRNA/aminoacyl-tRNA synthetase systemis described in Chin, J. W., et al., J. Am. Chem. Soc. 124:9026-9027(2002). Exemplary O-RS sequences for p-azido-L-Phe include, but are notlimited to, nucleotide sequences SEQ ID NOs: 14-16 and 29-32 and aminoacid sequences SEQ ID NOs: 46-48 and 61-64 as disclosed in U.S. PatentApplication Publication 2003/0108885 (Ser. No. 10/126,931) which isincorporated by reference herein. Exemplary O-tRNA sequences suitablefor use in the present invention include, but are not limited to,nucleotide sequences SEQ ID NOs: 1-3 as disclosed in U.S. PatentApplication Publication 2003/0108885 (Ser. No. 10/126,931) which isincorporated by reference herein. Other examples ofO-tRNA/aminoacyl-tRNA synthetase pairs specific to particularnon-naturally encoded amino acids are described in U.S. PatentApplication Publication 2003/0082575 (Ser. No. 10/126,927) which isincorporated by reference herein. O-RS and O-tRNA that incorporate bothketo- and azide-containing amino acids in S. cerevisiae are described inChin, J. W., et al., Science 301:964-967 (2003).

Use of O-tRNA/aminoacyl-tRNA synthetases involves selection of aspecific codon which encodes the non-naturally encoded amino acid. Whileany codon can be used, it is generally desirable to select a codon thatis rarely or never used in the cell in which the O-tRNA/aminoacyl-tRNAsynthetase is expressed. For example, exemplary codons include nonsensecodon such as stop codons (amber, ochre, and opal), four or more basecodons and other natural three-base codons that are rarely or unused.

Specific selector codon(s) can be introduced into appropriate positionsin the hGH polynucleotide coding sequence using mutagenesis methodsknown in the art (including but not limited to, site-specificmutagenesis, cassette mutagenesis, restriction selection mutagenesis,etc.).

Methods for generating components of the protein biosynthetic machinery,such as O-RSs, O-tRNAs, and orthogonal O-tRNA/O-RS pairs that can beused to incorporate a non-naturally encoded amino acid are described inWang, L., et al., Science 292: 498-500 (2001); Chin, J. W., et al., J.Am. Chem. Soc. 124:9026-9027 (2002); Zhang, Z. et al., Biochemistry 42:6735-6746 (2003). Methods and compositions for the in vivo incorporationof non-naturally encoded amino acids are described in U.S. PatentApplication Publication 2003/0082575 (Ser. No. 10/126,927) which isincorporated by reference herein. Methods for selecting an orthogonaltRNA-tRNA synthetase pair for use in in vivo translation system of anorganism are also described in U.S. Patent Application Publications2003/0082575 (Ser. No. 10/126,927) and 2003/0108885 (Ser. No.10/126,931) which are incorporated by reference herein.

Methods for producing at least one recombinant orthogonal aminoacyl-tRNAsynthetase (O-RS) comprise: (a) generating a library of (optionallymutant) RSs derived from at least one aminoacyl-tRNA synthetase (RS)from a first organism, including but not limited to, a prokaryoticorganism, such as Methanococcus jannaschii, Methanobacteriumthermoautotrophicum, Halobacterium, Escherichia coli, A. fulgidus, P.furiosus, P. horikoshii, A. pernix, T. thermophilus, or the like, or aeukaryotic organism; (b) selecting (and/or screening) the library of RSs(optionally mutant RSs) for members that aminoacylate an orthogonal tRNA(O-tRNA) in the presence of a non-naturally encoded amino acid and anatural amino acid, thereby providing a pool of active (optionallymutant) RSs; and/or, (c) selecting (optionally through negativeselection) the pool for active RSs (including but not limited to, mutantRSs) that preferentially aminoacylate the O-tRNA in the absence of thenon-naturally encoded amino acid, thereby providing the at least onerecombinant O-RS; wherein the at least one recombinant O-RSpreferentially aminoacylates the O-tRNA with the non-naturally encodedamino acid.

In one embodiment, the RS is an inactive RS. The inactive RS can begenerated by mutating an active RS. For example, the inactive RS can begenerated by mutating at least about 1, at least about 2, at least about3, at least about 4, at least about 5, at least about 6, or at leastabout 10 or more amino acids to different amino acids, including but notlimited to, alanine.

Libraries of mutant RSs can be generated using various techniques knownin the art, including but not limited to rational design based onprotein three dimensional RS structure, or mutagenesis of RS nucleotidesin a random or rational design technique. For example, the mutant RSscan be generated by site-specific mutations, random mutations, diversitygenerating recombination mutations, chimeric constructs, rational designand by other methods described herein or known in the art.

In one embodiment, selecting (and/or screening) the library of RSs(optionally mutant RSs) for members that are active, including but notlimited to, that aminoacylate an orthogonal tRNA (O-tRNA) in thepresence of a non-naturally encoded amino acid and a natural amino acid,includes: introducing a positive selection or screening marker,including but not limited to, an antibiotic resistance gene, or thelike, and the library of (optionally mutant) RSs into a plurality ofcells, wherein the positive selection and/or screening marker comprisesat least one selector codon, including but not limited to, an amber,ochre, or opal codon; growing the plurality of cells in the presence ofa selection agent; identifying cells that survive (or show a specificresponse) in the presence of the selection and/or screening agent bysuppressing the at least one selector codon in the positive selection orscreening marker, thereby providing a subset of positively selectedcells that contains the pool of active (optionally mutant) RSs.Optionally, the selection and/or screening agent concentration can bevaried.

In one aspect, the positive selection marker is a chloramphenicolacetyltransferase (CAT) gene and the selector codon is an amber stopcodon in the CAT gene. Optionally, the positive selection marker is aβ-lactamase gene and the selector codon is an amber stop codon in theβ-lactamase gene. In another aspect the positive screening markercomprises a fluorescent or luminescent screening marker or an affinitybased screening marker (including but not limited to, a cell surfacemarker).

In one embodiment, negatively selecting or screening the pool for activeRSs (optionally mutants) that preferentially aminoacylate the O-tRNA inthe absence of the non-naturally encoded amino acid includes:introducing a negative selection or screening marker with the pool ofactive (optionally mutant) RSs from the positive selection or screeninginto a plurality of cells of a second organism, wherein the negativeselection or screening marker comprises at least one selector codon(including but not limited to, an antibiotic resistance gene, includingbut not limited to, a chloramphenicol acetyltransferase (CAT) gene);and, identifying cells that survive or show a specific screeningresponse in a first medium supplemented with the non-naturally encodedamino acid and a screening or selection agent, but fail to survive or toshow the specific response in a second medium not supplemented with thenon-naturally encoded amino acid and the selection or screening agent,thereby providing surviving cells or screened cells with the at leastone recombinant O-RS. For example, a CAT identification protocoloptionally acts as a positive selection and/or a negative screening indetermination of appropriate O-RS recombinants. For instance, a pool ofclones is optionally replicated on growth plates containing CAT (whichcomprises at least one selector codon) either with or without one ormore non-naturally encoded amino acid. Colonies growing exclusively onthe plates containing non-naturally encoded amino acids are thusregarded as containing recombinant O-RS. In one aspect, theconcentration of the selection (and/or screening) agent is varied. Insome aspects the first and second organisms are different. Thus, thefirst and/or second organism optionally comprises: a prokaryote, aeukaryote, a mammal, an Escherichia coli, a fungi, a yeast, anarchaebacterium, a eubacterium, a plant, an insect, a protist, etc. Inother embodiments, the screening marker comprises a fluorescent orluminescent screening marker or an affinity based screening marker.

In another embodiment, screening or selecting (including but not limitedto, negatively selecting) the pool for active (optionally mutant) RSsincludes: isolating the pool of active mutant RSs from the positiveselection step (b); introducing a negative selection or screeningmarker, wherein the negative selection or screening marker comprises atleast one selector codon (including but not limited to, a toxic markergene, including but not limited to, a ribonuclease barnase gene,comprising at least one selector codon), and the pool of active(optionally mutant) RSs into a plurality of cells of a second organism;and identifying cells that survive or show a specific screening responsein a first medium not supplemented with the non-naturally encoded aminoacid, but fail to survive or show a specific screening response in asecond medium supplemented with the non-naturally encoded amino acid,thereby providing surviving or screened cells with the at least onerecombinant O-RS, wherein the at least one recombinant O-RS is specificfor the non-naturally encoded amino acid. In one aspect, the at leastone selector codon comprises about two or more selector codons. Suchembodiments optionally can include wherein the at least one selectorcodon comprises two or more selector codons, and wherein the first andsecond organism are different (including but not limited to, eachorganism is optionally, including but not limited to, a prokaryote, aeukaryote, a mammal, an Escherichia coli, a fungi, a yeast, anarchaebacteria, a eubacteria, a plant, an insect, a protist, etc.).Also, some aspects include wherein the negative selection markercomprises a ribonuclease barnase gene (which comprises at least oneselector codon). Other aspects include wherein the screening markeroptionally comprises a fluorescent or luminescent screening marker or anaffinity based screening marker. In the embodiments herein, thescreenings and/or selections optionally include variation of thescreening and/or selection stringency.

In one embodiment, the methods for producing at least one recombinantorthogonal aminoacyl-tRNA synthetase (O-RS) can further comprise: (d)isolating the at least one recombinant O-RS; (e) generating a second setof O-RS (optionally mutated) derived from the at least one recombinantO-RS; and, (f) repeating steps (b) and (c) until a mutated O-RS isobtained that comprises an ability to preferentially aminoacylate theO-tRNA. Optionally, steps (d)-(f) are repeated, including but notlimited to, at least about two times. In one aspect, the second set ofmutated O-RS derived from at least one recombinant O-RS can be generatedby mutagenesis, including but not limited to, random mutagenesis,site-specific mutagenesis, recombination or a combination thereof.

The stringency of the selection/screening steps, including but notlimited to, the positive selection/screening step (b), the negativeselection/screening step (c) or both the positive and negativeselection/screening steps (b) and (c), in the above-described methods,optionally includes varying the selection/screening stringency. Inanother embodiment, the positive selection/screening step (b), thenegative selection/screening step (c) or both the positive and negativeselection/screening steps (b) and (c) comprise using a reporter, whereinthe reporter is detected by fluorescence-activated cell sorting (FACS)or wherein the reporter is detected by luminescence. Optionally, thereporter is displayed on a cell surface, on a phage display or the likeand selected based upon affinity or catalytic activity involving thenon-naturally encoded amino acid or an analogue. In one embodiment, themutated synthetase is displayed on a cell surface, on a phage display orthe like.

Methods for producing a recombinant orthogonal tRNA (O-tRNA) include:(a) generating a library of mutant tRNAs derived from at least one tRNA,including but not limited to, a suppressor tRNA, from a first organism;(b) selecting (including but not limited to, negatively selecting) orscreening the library for (optionally mutant) tRNAs that areaminoacylated by an aminoacyl-tRNA synthetase (RS) from a secondorganism in the absence of a RS from the first organism, therebyproviding a pool of tRNAs (optionally mutant); and, (c) selecting orscreening the pool of tRNAs (optionally mutant) for members that areaminoacylated by an introduced orthogonal RS (O-RS), thereby providingat least one recombinant O-tRNA; wherein the at least one recombinantO-tRNA recognizes a selector codon and is not efficiency recognized bythe RS from the second organism and is preferentially aminoacylated bythe O-RS. In some embodiments the at least one tRNA is a suppressor tRNAand/or comprises a unique three base codon of natural and/or unnaturalbases, or is a nonsense codon, a rare codon, an unnatural codon, a codoncomprising at least 4 bases, an amber codon, an ochre codon, or an opalstop codon. In one embodiment, the recombinant O-tRNA possesses animprovement of orthogonality. It will be appreciated that in someembodiments, O-tRNA is optionally imported into a first organism from asecond organism without the need for modification. In variousembodiments, the first and second organisms are either the same ordifferent and are optionally chosen from, including but not limited to,prokaryotes (including but not limited to, Methanococcus jannaschii,Methanobacteium thermoautotrophicum, Escherichia coli, Halobacterium,etc.), eukaryotes, mammals, fungi, yeasts, archaebacteria, eubacteria,plants, insects, protists, etc. Additionally, the recombinant tRNA isoptionally aminoacylated by a non-naturally encoded amino acid, whereinthe non-naturally encoded amino acid is biosynthesized in vivo eithernaturally or through genetic manipulation. The non-naturally encodedamino acid is optionally added to a growth medium for at least the firstor second organism.

In one aspect, selecting (including but not limited to, negativelyselecting) or screening the library for (optionally mutant) tRNAs thatare aminoacylated by an aminoacyl-tRNA synthetase (step (b)) includes:introducing a toxic marker gene, wherein the toxic marker gene comprisesat least one of the selector codons (or a gene that leads to theproduction of a toxic or static agent or a gene essential to theorganism wherein such marker gene comprises at least one selector codon)and the library of (optionally mutant) tRNAs into a plurality of cellsfrom the second organism; and, selecting surviving cells, wherein thesurviving cells contain the pool of (optionally mutant) tRNAs comprisingat least one orthogonal tRNA or nonfunctional tRNA. For example,surviving cells can be selected by using a comparison ratio cell densityassay.

In another aspect, the toxic marker gene can include two or moreselector codons. In another embodiment of the methods, the toxic markergene is a ribonuclease barnase gene, where the ribonuclease barnase genecomprises at least one amber codon. Optionally, the ribonuclease barnasegene can include two or more amber codons.

In one embodiment, selecting or screening the pool of (optionallymutant) tRNAs for members that are aminoacylated by an introducedorthogonal RS (O-RS) can include: introducing a positive selection orscreening marker gene, wherein the positive marker gene comprises a drugresistance gene (including but not limited to, β-lactamase gene,comprising at least one of the selector codons, such as at least oneamber stop codon) or a gene essential to the organism, or a gene thatleads to detoxification of a toxic agent, along with the O-RS, and thepool of (optionally mutant) tRNAs into a plurality of cells from thesecond organism; and, identifying surviving or screened cells grown inthe presence of a selection or screening agent, including but notlimited to, an antibiotic, thereby providing a pool of cells possessingthe at least one recombinant tRNA, where the at least one recombinanttRNA is aminoacylated by the O-RS and inserts an amino acid into atranslation product encoded by the positive marker gene, in response tothe at least one selector codons. In another embodiment, theconcentration of the selection and/or screening agent is varied.

Methods for generating specific O-tRNA/O-RS pairs are provided. Methodsinclude: (a) generating a library of mutant tRNAs derived from at leastone tRNA from a first organism; (b) negatively selecting or screeningthe library for (optionally mutant) tRNAs that are aminoacylated by anaminoacyl-tRNA synthetase (RS) from a second organism in the absence ofa RS from the first organism, thereby providing a pool of (optionallymutant) tRNAs; (c) selecting or screening the pool of (optionallymutant) tRNAs for members that are aminoacylated by an introducedorthogonal RS (O-RS), thereby providing at least one recombinant O-tRNA.The at least one recombinant O-tRNA recognizes a selector codon and isnot efficiency recognized by the RS from the second organism and ispreferentially aminoacylated by the O-RS. The method also includes (d)generating a library of (optionally mutant) RSs derived from at leastone aminoacyl-tRNA synthetase (RS) from a third organism; (e) selectingor screening the library of mutant RSs for members that preferentiallyaminoacylate the at least one recombinant O-tRNA in the presence of anon-naturally encoded amino acid and a natural amino acid, therebyproviding a pool of active (optionally mutant) RSs; and, (f) negativelyselecting or screening the pool for active (optionally mutant) RSs thatpreferentially aminoacylate the at least one recombinant O-tRNA in theabsence of the non-naturally encoded amino acid, thereby providing theat least one specific O-tRNA/O-RS pair, wherein the at least onespecific O-tRNA/O-RS pair comprises at least one recombinant O-RS thatis specific for the non-naturally encoded amino acid and the at leastone recombinant O-tRNA. Specific O-tRNA/O-RS pairs produced by themethods are included. For example, the specific O-tRNA/O-RS pair caninclude, including but not limited to, a mutRNATyr-mutTyrRS pair, suchas a mutRNATyr-SS12TyrRS pair, a mutRNALeu-mutLeuRS pair, amutRNAThr-mutThrRS pair, a mutRNAGlu-mutGluRS pair, or the like.Additionally, such methods include wherein the first and third organismare the same (including but not limited to, Methanococcus jannaschii).

Methods for selecting an orthogonal tRNA-tRNA synthetase pair for use inan in vivo translation system of a second organism are also included inthe present invention. The methods include: introducing a marker gene, atRNA and an aminoacyl-tRNA synthetase (RS) isolated or derived from afirst organism into a first set of cells from the second organism;introducing the marker gene and the tRNA into a duplicate cell set froma second organism; and, selecting for surviving cells in the first setthat fail to survive in the duplicate cell set or screening for cellsshowing a specific screening response that fail to give such response inthe duplicate cell set, wherein the first set and the duplicate cell setare grown in the presence of a selection or screening agent, wherein thesurviving or screened cells comprise the orthogonal tRNA-tRNA synthetasepair for use in the in the in vivo translation system of the secondorganism. In one embodiment, comparing and selecting or screeningincludes an in vivo complementation assay. The concentration of theselection or screening agent can be varied.

The organisms of the present invention comprise a variety of organismand a variety of combinations. For example, the first and the secondorganisms of the methods of the present invention can be the same ordifferent. In one embodiment, the organisms are optionally a prokaryoticorganism, including but not limited to, Methanococcus jannaschii,Methanobacterium thermoautotrophicum, Halobacterium, Escherichia coli,A. fulgidus, P. furiosus, P. horikoshii, A. pernix, T. thermophilus, orthe like. Alternatively, the organisms optionally comprise a eukaryoticorganism, including but not limited to, plants (including but notlimited to, complex plants such as monocots, or dicots), algae,protists, fungi (including but not limited to, yeast, etc), animals(including but not limited to, mammals, insects, arthropods, etc.), orthe like. In another embodiment, the second organism is a prokaryoticorganism, including but not limited to, Methanococcus jannaschii,Methanobacterium thermoautotrophicum, Halobacterium, Escherichia coli,A. fulgidus, Halobacterium, P. furiosus, P. horikoshii, A. pernix, T.thermophilus, or the like. Alternatively, the second organism can be aeukaryotic organism, including but not limited to, a yeast, a animalcell, a plant cell, a fungus, a mammalian cell, or the like. In variousembodiments the first and second organisms are different.

VI. Location of Non-Naturally-Occurring Amino Acids in hGH Polypeptides

The present invention contemplates incorporation of one or morenon-naturally-occurring amino acids into hGH polypeptides. One or morenon-naturally-occurring amino acids may be incorporated at a particularposition which does not disrupt activity of the polypeptide. This can beachieved by making “conservative” substitutions, including but notlimited to, substituting hydrophobic amino acids with hydrophobic aminoacids, bulky amino acids for bulky amino acids, hydrophilic amino acidsfor hydrophilic amino acids) and/or inserting thenon-naturally-occurring amino acid in a location that is not requiredfor activity.

Regions of hGH can be illustrated as follows, wherein the amino acidpositions in hGH are indicated in the middle row (SEQ ID NO: 2):

A variety of biochemical and structural approaches can be employed toselect the desired sites for substitution with a non-naturally encodedamino acid within the hGH polypeptide. It is readily apparent to thoseof ordinary skill in the art that any position of the polypeptide chainis suitable for selection to incorporate a non-naturally encoded aminoacid, and selection may be based on rational design or by randomselection for any or no particular desired purpose. Selection of desiredsites may be for producing a hGH molecule having any desired property oractivity, including but not limited to, agonists, super-agonists,inverse agonists, antagonists, receptor binding modulators, receptoractivity modulators, dimer or multimer formation, no change to activityor property compared to the native molecule, or manipulating anyphysical or chemical property of the polypeptide such as solubility,aggregation, or stability. For example, locations in the polypeptiderequired for biological activity of hGH polypeptides can be identifiedusing alanine scanning or homolog scanning methods known in the art.See, e.g., Cunningham, B. and Wells, J., Science, 244:1081-1085 (1989)(identifying 14 residues that are critical for hGH bioactivity) andCunningham, B., et al. Science 243: 1330-1336 (1989) (identifyingantibody and receptor epitopes using homolog scanning mutagenesis).Residues other than those identified as critical to biological activityby alanine or homolog scanning mutagenesis may be good candidates forsubstitution with a non-naturally encoded amino acid depending on thedesired activity sought for the polypeptide. Alternatively, the sitesidentified as critical to biological activity may also be goodcandidates for substitution with a non-naturally encoded amino acid,again depending on the desired activity sought for the polypeptide.Another alternative would be to simply make serial substitutions in eachposition on the polypeptide chain with a non-naturally encoded aminoacid and observe the effect on the activities of the polypeptide. It isreadily apparent to those of ordinary skill in the art that any means,technique, or method for selecting a position for substitution with anon-natural amino acid into any polypeptide is suitable for use in thepresent invention.

The structure and activity of naturally-occurring mutants of hGHpolypeptides that contain deletions can also be examined to determineregions of the protein that are likely to be tolerant of substitutionwith a non-naturally encoded amino acid. See, e.g., Kostyo et al.,Biochem. Biophys. Acta, 925: 314 (1987); Lewis, U., et al., J. Biol.Chem., 253:2679-2687 (1978) for hGH. In a similar manner, proteasedigestion and monoclonal antibodies can be used to identify regions ofhGH that are responsible for binding the hGH receptor. See, e.g.,Cunningham, B., et al. Science 243: 1330-1336 (1989); Mills, J., et al.,Endocrinology, 107:391-399 (1980); Li, C., Mol. Cell. Biochem., 46:31-41(1982) (indicating that amino acids between residues 134-149 can bedeleted without a loss of activity). Once residues that are likely to beintolerant to substitution with non-naturally encoded amino acids havebeen eliminated, the impact of proposed substitutions at each of theremaining positions can be examined from the three-dimensional crystalstructure of the hGH and its binding proteins. See de Vos, A., et al.,Science, 255:306-312 (1992) for hGH; all crystal structures of hGH areavailable in the Protein Data Bank (including 3HHR, 1AXI, and 1HWG)(PDB, available on the World Wide Web at rcsb.org), a centralizeddatabase containing three-dimensional structural data of large moleculesof proteins and nucleic acids. Thus, those of skill in the art canreadily identify amino acid positions that can be substituted withnon-naturally encoded amino acids.

In some embodiments, the hGH polypeptides of the invention comprise oneor more non-naturally occurring amino acids positioned in a region ofthe protein that does not disrupt the helices or beta sheet secondarystructure of the polypeptide.

Exemplary residues of incorporation of a non-naturally encoded aminoacid may be those that are excluded from potential receptor bindingregions (including but not limited to, Site I and Site II), may be fullyor partially solvent exposed, have minimal or no hydrogen-bondinginteractions with nearby residues, may be minimally exposed to nearbyreactive residues, and may be in regions that are highly flexible(including but not limited to, C-D loop) or structurally rigid(including but not limited to, B helix) as predicted by thethree-dimensional crystal structure of the hGH polypeptide with itsreceptor.

In some embodiments, one or more non-naturally encoded amino acids areincorporated at any position in one or more of the following regionscorresponding to secondary structures in hGH as follows: 1-5(N-terminus), 6-33 (A helix), 34-74 (region between A helix and B helix,the A-B loop), 75-96 (B helix), 97-105 (region between B helix and Chelix, the B-C loop), 106-129 (C helix), 130-153 (region between C helixand D helix, the C-D loop), 154-183 (D helix), 184-191 (C-terminus) fromSEQ ID NO: 2. In other embodiments, hGH polypeptides of the inventioncomprise at least one non-naturally-occurring amino acid substituted forat least one amino acid located in at least one region of hGH selectedfrom the group consisting of the N-terminus (1-5), the N-terminal end ofthe A-B loop (32-46); the B-C loop (97-105), the C-D loop (132-149), andthe C-terminus (184-191). In some embodiments, one or more non-naturallyencoded amino acids are incorporated at one or more of the followingpositions of hGH: before position 1 (i.e. at the N-terminus), 1, 2, 3,4, 5, 8, 9, 11, 12, 15, 16, 19, 22, 29, 30, 32, 33, 34, 35, 36, 37, 38,39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 52, 55, 57, 59, 65, 66, 69,70, 71, 74, 88, 91, 92, 94, 95, 97, 98, 99, 100, 101, 102, 103, 104,105, 106, 107, 108, 109, 111, 112, 113, 115, 116, 119, 120, 122, 123,126, 127, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140,141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154,155, 156, 158, 159, 161, 168, 172, 183, 184, 185, 186, 187, 188, 189,190, 191, 192 (i.e., at the carboxyl terminus of the protein) (SEQ IDNO: 2 or the corresponding amino acids of SEQ ID NO: 1 or 3).

Exemplary sites of incorporation of one or more non-naturally encodedamino acids include 29, 30, 33, 34, 35, 37, 39, 40, 49, 57, 59, 66, 69,70, 71, 74, 88, 91, 92, 94, 95, 98, 99, 101, 103, 107, 108, 111, 122,126, 129, 130, 131, 133, 134, 135, 136, 137, 139, 140, 141, 142, 143,145, 147, 154, 155, 156, 159, 183, 186, and 187, or any combinationthereof from SEQ ID NO: 2 or the corresponding amino acids of SEQ ID NO:1 or 3.

A subset of exemplary sites for incorporation of one or morenon-naturally encoded amino acid include 29, 33, 35, 37, 39, 49, 57, 69,70, 71, 74, 88, 91, 92, 94, 95, 98, 99, 101, 103, 107, 108, 111, 129,130, 131, 133, 134, 135, 136, 137, 139, 140, 141, 142, 143, 145, 147,154, 155, 156, 186, and 187, or any combination thereof from SEQ ID NO:2 or the corresponding amino acids of SEQ ID NO: 1 or 3. An examinationof the crystal structure of hGH and its interactions with the hGHreceptor indicates that the side chains of these amino acid residues arefully or partially accessible to solvent and the side chain of anon-naturally encoded amino acid may point away from the protein surfaceand out into the solvent.

Exemplary positions for incorporation of one or more non-naturallyencoded amino acids include 35, 88, 91, 92, 94, 95, 99, 101, 103, 111,131, 133, 134, 135, 136, 139, 140, 143, 145, and 155, or any combinationthereof from SEQ ID NO: 2 or the corresponding amino acids of SEQ ID NO:1 or 3. An examination of the crystal structure of hGH and itsinteractions with the hGH receptor indicates that the side chains ofthese amino acid residues are fully exposed to the solvent and the sidechain of the native residue points out into the solvent.

A subset of exemplary sites for incorporation of one or morenon-naturally encoded amino acids include 30, 74, 103, or anycombination thereof, from SEQ ID NO: 2 or the corresponding amino acidsof SEQ ID NO: 1 or 3. Another subset of exemplary sites forincorporation of one or more non-naturally encoded amino acids include35, 92, 143, 145, or any combination thereof, from SEQ ID NO: 2 or thecorresponding amino acids of SEQ ID NO: 1 or 3.

In some embodiments, the non-naturally occurring amino acid at one ormore of these positions is linked to a water soluble polymer, includingbut not limited to, positions: before position 1 (i.e. at theN-terminus), 1, 2, 3, 4, 5, 8, 9, 11, 12, 15, 16, 19, 22, 29, 30, 32,33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 52,55, 57, 59, 65, 66, 69, 70, 71, 74, 88, 91, 92, 94, 95, 97, 98, 99, 100,101, 102, 103, 104, 105, 106, 107, 108, 109, 111, 112, 113, 115, 116,119, 120, 122, 123, 126, 127, 129, 130, 131, 132, 133, 134, 135, 136,137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150,151, 152, 153, 154, 155, 156, 158, 159, 161, 168, 172, 183, 184, 185,186, 187, 188, 189, 190, 191, 192 (i.e., at the carboxyl terminus of theprotein) (SEQ ID NO: 2 or the corresponding amino acids of SEQ ID NO: 1or 3). In some embodiments, the non-naturally occurring amino acid atone or more of these positions is linked to a water soluble polymer: 30,35, 74, 92, 103, 143, 145 (SEQ ID NO: 2 or the corresponding amino acidsof SEQ ID NO: 1 or 3). In some embodiments, the non-naturally occurringamino acid at one or more of these positions is linked to a watersoluble polymer: 35, 92, 143, 145 (SEQ ID NO: 2 or the correspondingamino acids of SEQ ID NO: 1 or 3).

Human GH antagonists include, but are not limited to, those withsubstitutions at: 1, 2, 3, 4, 5, 8, 9, 11, 12, 15, 16, 19, 22, 103, 109,112, 113, 115, 116, 119, 120, 123, and 127 or an addition at position 1(i.e., at the N-terminus), or any combination thereof (SEQ ID NO:2, orthe corresponding amino acid in SEQ ID NO: 1, 3, or any other GHsequence).

A wide variety of non-naturally encoded amino acids can be substitutedfor, or incorporated into, a given position in a hGH polypeptide. Ingeneral, a particular non-naturally encoded amino acid is selected forincorporation based on an examination of the three dimensional crystalstructure of a hGH polypeptide with its receptor, a preference forconservative substitutions (i.e., aryl-based non-naturally encoded aminoacids, such as p-acetylphenylalanine or O-propargyltyrosine substitutingfor Phe, Tyr or Trp), and the specific conjugation chemistry that onedesires to introduce into the hGH polypeptide (e.g., the introduction of4-azidophenylalanine if one wants to effect a Huisgen [3+2]cycloaddition with a water soluble polymer bearing an alkyne moiety or aamide bond formation with a water soluble polymer that bears an arylester that, in turn, incorporates a phosphine moiety).

In one embodiment, the method further includes incorporating into theprotein the unnatural amino acid, where the unnatural amino acidcomprises a first reactive group; and contacting the protein with amolecule (including but not limited to, a label, a dye, a polymer, awater-soluble polymer, a derivative of polyethylene glycol, aphotocrosslinker, a cytotoxic compound, a drug, an affinity label, aphotoaffinity label, a reactive compound, a resin, a second protein orpolypeptide or polypeptide analog, an antibody or antibody fragment, ametal chelator, a cofactor, a fatty acid, a carbohydrate, apolynucleotide, a DNA, a RNA, an antisense polynucleotide, an inhibitoryribonucleic acid, a biomaterial, a nanoparticle, a spin label, afluorophore, a metal-containing moiety, a radioactive moiety, a novelfunctional group, a group that covalently or noncovalently interactswith other molecules, a photocaged moiety, a photoisomerizable moiety,biotin, a derivative of biotin, a derivative of biotin, a biotinanalogue, a moiety incorporating a heavy atom, a chemically cleavablegroup, a photocleavable group, an elongated side chain, a carbon-linkedsugar, a redox-active agent, an amino thioacid, a toxic moiety, anisotopically labeled moiety, a biophysical probe, a phosphorescentgroup, a chemiluminescent group, an electron dense group, a magneticgroup, an intercalating group, a chromophore, an energy transfer agent,a biologically active agent, a detectable label, a small molecule, orany combination of the above, or any other desirable compound orsubstance) that comprises a second reactive group. The first reactivegroup reacts with the second reactive group to attach the molecule tothe unnatural amino acid through a [3+2] cycloaddition. In oneembodiment, the first reactive group is an alkynyl or azido moiety andthe second reactive group is an azido or alkynyl moiety. For example,the first reactive group is the alkynyl moiety (including but notlimited to, in unnatural amino acid p-propargyloxyphenylalanine) and thesecond reactive group is the azido moiety. In another example, the firstreactive group is the azido moiety (including but not limited to, in theunnatural amino acid p-azido-L-phenylalanine) and the second reactivegroup is the alkynyl moiety.

In some cases, the non-naturally encoded amino acid substitution(s) willbe combined with other additions, substitutions or deletions within thehGH polypeptide to affect other biological traits of the hGHpolypeptide. In some cases, the other additions, substitutions ordeletions may increase the stability (including but not limited to,resistance to proteolytic degradation) of the hGH polypeptide orincrease affinity of the hGH polypeptide for its receptor. In someembodiments, the hGH polypeptide comprises an amino acid substitutionselected from the group consisting of F10A, F10H, F10I; M14W, M14Q,M14G; H18D; H21N; G120A; R167N; D171S; E174S; F176Y, I179T or anycombination thereof in SEQ ID NO: 2. In some cases, the other additions,substitutions or deletions may increase the solubility (including butnot limited to, when expressed in E. coli or other host cells) of thehGH polypeptide. In some embodiments additions, substitutions ordeletions may increase the polypeptide solubility following expressionin E. coli recombinant host cells. In some embodiments sites areselected for substitution with a naturally encoded or non-natural aminoacid in addition to another site for incorporation of a non-naturalamino acid that results in increasing the polypeptide solubilityfollowing expression in E. coli recombinant host cells. In someembodiments, the hGH polypeptides comprise another addition,substitution or deletion that modulates affinity for the hGH polypeptidereceptor, modulates (including but not limited to, increases ordecreases) receptor dimerization, stabilizes receptor dimers, modulatescirculating half-life, modulates release or bio-availability,facilitates purification, or improves or alters a particular route ofadministration. For instance, in addition to introducing one or morenon-naturally encoded amino acids as set forth herein, one or more ofthe following substitutions are introduced: F10A, F10H or F10I; M14W,M14Q, or M14G; H18D; H21N; R167N; D171S; E174S; F176Y and I179T toincrease the affinity of the hGH variant for its receptor. Similarly,hGH polypeptides can comprise protease cleavage sequences, reactivegroups, antibody-binding domains (including but not limited to, FLAG orpoly-His) or other affinity based sequences (including, but not limitedto, FLAG, poly-His, GST, etc.) or linked molecules (including, but notlimited to, biotin) that improve detection (including, but not limitedto, GFP), purification or other traits of the polypeptide.

In some embodiments, the substitution of a non-naturally encoded aminoacid generates an hGH antagonist. A subset of exemplary sites forincorporation of one or more non-naturally encoded amino acid include:1, 2, 3, 4, 5, 8, 9, 11, 12, 15, 16, 19, 22, 103, 109, 112, 113, 115,116, 119, 120, 123, 127, or an addition before position 1 (SEQ ID NO: 2,or the corresponding amino acid in SEQ ID NO: 1, 3, or any other GHsequence). In some embodiments, hGH antagonists comprise at least onesubstitution in the regions 1-5 (N-terminus), 6-33 (A helix), 34-74(region between A helix and B helix, the A-B loop), 75-96 (B helix),97-105 (region between B helix and C helix, the B-C loop), 106-129 (Chelix), 130-153 (region between C helix and D helix, the C-D loop),154-183 (D helix), 184-191 (C-terminus) that cause GH to act as anantagonist. In other embodiments, the exemplary sites of incorporationof a non-naturally encoded amino acid include residues within the aminoterminal region of helix A and a portion of helix C. In anotherembodiment, substitution of G120 with a non-naturally encoded amino acidsuch as p-azido-L-phenyalanine or O-propargyl-L-tyrosine. In otherembodiments, the above-listed substitutions are combined with additionalsubstitutions that cause the hGH polypeptide to be an hGH antagonist.For instance, a non-naturally encoded amino acid is substituted at oneof the positions identified herein and a simultaneous substitution isintroduced at G120 (e.g., G120R, G120K, G120W, G120Y, G120F, or G120E).In some embodiments, the hGH antagonist comprises a non-naturallyencoded amino acid linked to a water soluble polymer that is present ina receptor binding region of the hGH molecule.

In some cases, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or more amino acids aresubstituted with one or more non-naturally-encoded amino acids. In somecases, the hGH polypeptide further includes 1, 2, 3, 4, 5, 6, 7, 8, 9,10, or more substitutions of one or more non-naturally encoded aminoacids for naturally-occurring amino acids. For example, in someembodiments, at least two residues in the following regions of hGH aresubstituted with one or more non-naturally encoded amino acids: 1-5(N-terminus); 32-46 (N-terminal end of the A-B loop); 97-105 (B-C loop);and 132-149 (C-D loop); and 184-191 (C-terminus). In some embodiments,at least two residues in the following regions of hGH are substitutedwith one or more non-naturally encoded amino acids: 1-5 (N-terminus),6-33 (A helix), 34-74 (region between A helix and B helix, the A-Bloop), 75-96 (B helix), 97-105 (region between B helix and C helix, theB-C loop), 106-129 (C helix), 130-153 (region between C helix and Dhelix, the C-D loop), 154-183 (D helix), 184-191 (C-terminus). In somecases, the two or more non-naturally encoded residues are linked to oneor more lower molecular weight linear or branched PEGs (approximately˜5-20 kDa in mass or less), thereby enhancing binding affinity andcomparable serum half-life relative to the species attached to a single,higher molecular weight PEG.

In some embodiments, up to two of the following residues of hGH aresubstituted with one or more non-naturally-encoded amino acids atposition: 29, 30, 33, 34, 35, 37, 39, 40, 49, 57, 59, 66, 69, 70, 71,74, 88, 91, 92, 94, 95, 98, 99, 101, 103, 107, 108, 111, 122, 126, 129,130, 131, 133, 134, 135, 136, 137, 139, 140, 141, 142, 143, 145, 147,154, 155, 156, 159, 183, 186, and 187. In some cases, any of thefollowing pairs of substitutions are made: K38X* and K140X*; K41X* andK145X*; Y35X* and E88X*; Y35X* and F92X*; Y35X* and Y143X*; F92X* andY143X* wherein X* represents a non-naturally encoded amino acid.Preferred sites for incorporation of two or more non-naturally encodedamino acids include combinations of the following residues: 29, 33, 35,37, 39, 49, 57, 69, 70, 71, 74, 88, 91, 92, 94, 95, 98, 99, 101, 103,107, 108, 111, 129, 130, 131, 133, 134, 135, 136, 137, 139, 140, 141,142, 143, 145, 147, 154, 155, 156, 186, and 187. Particularly preferredsites for incorporation of two or more non-naturally encoded amino acidsinclude combinations of the following residues: 35, 88, 91, 92, 94, 95,99, 101, 103, 111, 131, 133, 134, 135, 136, 139, 140, 143, 145, and 155.

Preferred sites for incorporation in hGH of two or more non-naturallyencoded amino acids include combinations of the following residues:before position 1 (i.e. at the N-terminus), 1, 2, 3, 4, 5, 8, 9, 11, 12,15, 16, 19, 22, 29, 30, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43,44, 45, 46, 47, 48, 49, 52, 55, 57, 59, 65, 66, 69, 70, 71, 74, 88, 91,92, 94, 95, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108,109, 111, 112, 113, 115, 116, 119, 120, 122, 123, 126, 127, 129, 130,131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144,145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 158, 159,161, 168, 172, 183, 184, 185, 186, 187, 188, 189, 190, 191, 192 (i.e. atthe carboxyl terminus of the protein) or any combination thereof fromSEQ ID NO: 2.

VII. Expression in Non-Eukaryotes and Eukaryotes

To obtain high level expression of a cloned hGH polynucleotide, onetypically subclones polynucleotides encoding a hGH polypeptide of theinvention into an expression vector that contains a strong promoter todirect transcription, a transcription/translation terminator, and if fora nucleic acid encoding a protein, a ribosome binding site fortranslational initiation. Suitable bacterial promoters are well known inthe art and described, e.g., in Sambrook et al. and Ausubel et al.

Bacterial expression systems for expressing hGH polypeptides of theinvention are available in, including but not limited to, E. coli,Bacillus sp., and Salmonella (Palva et al., Gene 22:229-235 (1983);Mosbach et al., Nature 302:543-545 (1983)). Kits for such expressionsystems are commercially available. Eukaryotic expression systems formammalian cells, yeast, and insect cells are well known in the art andare also commercially available. In cases where orthogonal tRNAs andaminoacyl tRNA synthetases (described above) are used to express the hGHpolypeptides of the invention, host cells for expression are selectedbased on their ability to use the orthogonal components. Exemplary hostcells include Gram-positive bacteria (including but not limited to B.brevis, B. subtilis, or Streptomyces) and Gram-negative bacteria (E.coli, Pseudomonas fluorescens, Pseudomonas aeruginosa, Pseudomonasputida), as well as yeast and other eukaryotic cells. Cells comprisingO-tRNA/O-RS pairs can be used as described herein.

A eukaryotic host cell or non-eukaryotic host cell of the presentinvention provides the ability to synthesize proteins that compriseunnatural amino acids in large useful quantities. In one aspect, thecomposition optionally includes, including but not limited to, at least10 micrograms, at least 50 micrograms, at least 75 micrograms, at least100 micrograms, at least 200 micrograms, at least 250 micrograms, atleast 500 micrograms, at least 1 milligram, at least 10 milligrams, atleast 100 milligrams, at least one gram, or more of the protein thatcomprises an unnatural amino acid, or an amount that can be achievedwith in vivo protein production methods (details on recombinant proteinproduction and purification are provided herein). In another aspect, theprotein is optionally present in the composition at a concentration of,including but not limited to, at least 10 micrograms of protein perliter, at least 50 micrograms of protein per liter, at least 75micrograms of protein per liter, at least 100 micrograms of protein perliter, at least 200 micrograms of protein per liter, at least 250micrograms of protein per liter, at least 500 micrograms of protein perliter, at least 1 milligram of protein per liter, or at least 10milligrams of protein per liter or more, in, including but not limitedto, a cell lysate, a buffer, a pharmaceutical buffer, or other liquidsuspension (including but not limited to, in a volume of, including butnot limited to, anywhere from about 1 nl to about 100 L). The productionof large quantities (including but not limited to, greater that thattypically possible with other methods, including but not limited to, invitro translation) of a protein in a eukaryotic cell including at leastone unnatural amino acid is a feature of the invention.

A eukaryotic host cell or non-eukaryotic host cell of the presentinvention provides the ability to biosynthesize proteins that compriseunnatural amino acids in large useful quantities. For example, proteinscomprising an unnatural amino acid can be produced at a concentrationof, including but not limited to, at least 10 μg/liter, at least 50μg/liter, at least 75 μg/liter, at least 100 μg/liter, at least 200μg/liter, at least 250 μg/liter, or at least 500 μg/liter, at least 1mg/liter, at least 2 mg/liter, at least 3 mg/liter, at least 4 mg/liter,at least 5 mg/liter, at least 6 mg/liter, at least 7 mg/liter, at least8 mg/liter, at least 9 mg/liter, at least 10 mg/liter, at least 20, 30,40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, 900mg/liter, 1 g/liter, 5 g/liter, 10 g/liter or more of protein in a cellextract, cell lysate, culture medium, a buffer, and/or the like.

I. Expression Systems, Culture, and Isolation

hGH polypeptides may be expressed in any number of suitable expressionsystems including, for example, yeast, insect cells, mammalian cells,and bacteria. A description of exemplary expression systems is providedbelow.

Yeast As used herein, the term “yeast” includes any of the variousyeasts capable of expressing a gene encoding a hGH polypeptide. Suchyeasts include, but are not limited to, ascosporogenous yeasts(Endomycetales), basidiosporogenous yeasts and yeasts belonging to theFungi imperfecti (Blastomycetes) group. The ascosporogenous yeasts aredivided into two families, Spermophthoraceae and Saccharomycetaceae. Thelatter is comprised of four subfamilies, Schizosaccharomycoideae (e.g.,genus Schizosaccharomyces), Nadsonioideae, Lipomycoideae andSaccharomycoideae (e.g., genera Pichia, Kluyveromyces andSaccharomyces). The basidiosporogenous yeasts include the generaLeucosporidium, Rhodosporidium, Sporidiobolus, Filobasidium, andFilobasidiella. Yeasts belonging to the Fungi Imperfecti (Blastomycetes)group are divided into two families, Sporobolomycetaceae (e.g., generaSporobolomyces and Bullera) and Cryptococcaceae (e.g., genus Candida).

Of particular interest for use with the present invention are specieswithin the genera Pichia, Kluyveromyces, Saccharomyces,Schizosaccharomyces, Hansenula, Torulopsis, and Candida, including, butnot limited to, P. pastoris, P. guillerimondii, S. cerevisiae, S.carlsbergensis, S. diastaticus, S. douglasii, S. kluyveri, S, norbensis,S. oviformis, K. lactis, K. fragilis, C. albicans, C. maltosa, and H.polymorpha.

The selection of suitable yeast for expression of hGH polypeptides iswithin the skill of one of ordinary skill in the art. In selecting yeasthosts for expression, suitable hosts may include those shown to have,for example, good secretion capacity, low proteolytic activity, goodsecretion capacity, good soluble protein production, and overallrobustness. Yeast are generally available from a variety of sourcesincluding, but not limited to, the Yeast Genetic Stock Center,Department of Biophysics and Medical Physics, University of California(Berkeley, Calif.), and the American Type Culture Collection (“ATCC”)(Manassas, Va.).

The term “yeast host” or “yeast host cell” includes yeast that can be,or has been, used as a recipient for recombinant vectors or othertransfer DNA. The term includes the progeny of the original yeast hostcell that has received the recombinant vectors or other transfer DNA. Itis understood that the progeny of a single parental cell may notnecessarily be completely identical in morphology or in genomic or totalDNA complement to the original parent, due to accidental or deliberatemutation. Progeny of the parental cell that are sufficiently similar tothe parent to be characterized by the relevant property, such as thepresence of a nucleotide sequence encoding a hGH polypeptide, areincluded in the progeny intended by this definition.

Expression and transformation vectors, including extrachromosomalreplicons or integrating vectors, have been developed for transformationinto many yeast hosts. For example, expression vectors have beendeveloped for S. cerevisiae (Sikorski et al., GENETICS (1998) 112:19;Ito et al., J. BACTERIOL. (1983) 153:163; Hinnen et al., PROC. NATL.ACAD. SCI. USA (1978) 75:1929); C. albicans (Kurtz et al., MOL. CELL.BIOL. (1986) 6:142); C. maltosa (Kunze et al., J. BASIC MICROBIOL.(1985) 25:141); H. polymorpha (Gleeson et al., J. GEN. MICROBIOL. (1986)132:3459; Roggenkamp et al., MOL. GEN. GENET. (1986) 202:302); K.fragilis (Das et al., J. BACTERIOL. (1984) 158:1165); K lactis (DeLouvencourt et al., J. BACTERIOL. (1983) 154:737; Van den Berg et al.,BIO/TECHNOLOGY (1990) 8:135); P. guillerimondii (Kunze et al., J. BASICMICROBIOL. (1985) 25:141); P. pastoris (U.S. Pat. Nos. 5,324,639;4,929,555; and 4,837,148; Cregg et al., MOL. CELL. BIOL. (1985) 5:3376);Schizosaccharomyces pombe (Beach and Nurse, NATURE (1981) 300:706); andY. lipolytica (Davidow et al., CURR. GENET. (1985) 10:380 (1985);Gaillardin et al., CURR. GENET. (1985) 10:49); A. nidulans (Ballance etal., BIOCHEM. BIOPHYS. RES. COMMUN. (1983) 112:284-89; Tilburn et al.,GENE (1983) 26:205-221; and Yelton et al., PROC. NATL. ACAD. SCI. USA(1984) 81:1470-74); A. niger (Kelly and Hynes, EMBO J. (1985) 4:475479);T. reesia (EP 0 244 234); and filamentous fungi such as, e.g.,Neurospora, Penicillium, Tolypocladium (WO 91/00357), each incorporatedby reference herein.

Control sequences for yeast vectors are well known to those of ordinaryskill in the art and include, but are not limited to, promoter regionsfrom genes such as alcohol dehydrogenase (ADH) (EP 0 284 044); enolase;glucokinase; glucose-6-phosphate isomerase;glyceraldehydes-3-phosphate-dehydrogenase (GAP or GAPDH); hexokinase;phosphofructokinase; 3-phosphoglycerate mutase; and pyruvate kinase(PyK) (EP 0 329 203). The yeast PHO5 gene, encoding acid phosphatase,also may provide useful promoter sequences (Myanohara et al., PROC.NATL. ACAD. SCI. USA (1983) 80:1). Other suitable promoter sequences foruse with yeast hosts may include the promoters for 3-phosphoglyceratekinase (Hitzeman et al., J. BIOL. CHEM. (1980) 255:2073); and otherglycolytic enzymes, such as pyruvate decarboxylase, triosephosphateisomerase, and phosphoglucose isomerase (Holland et al., BIOCHEMISTRY(1978) 17:4900; Hess et al., J. ADV. ENZYME REG. (1968) 7:149).Inducible yeast promoters having the additional advantage oftranscription controlled by growth conditions may include the promoterregions for alcohol dehydrogenase 2; isocytochrome C; acid phosphatase;metallothionein; glyceraldehyde-3-phosphate dehydrogenase; degradativeenzymes associated with nitrogen metabolism; and enzymes responsible formaltose and galactose utilization. Suitable vectors and promoters foruse in yeast expression are further described in EP 0 073 657.

Yeast enhancers also may be used with yeast promoters. In addition,synthetic promoters may also function as yeast promoters. For example,the upstream activating sequences (UAS) of a yeast promoter may bejoined with the transcription activation region of another yeastpromoter, creating a synthetic hybrid promoter. Examples of such hybridpromoters include the ADH regulatory sequence linked to the GAPtranscription activation region. See U.S. Pat. Nos. 4,880,734 and4,876,197, which are incorporated by reference herein. Other examples ofhybrid promoters include promoters that consist of the regulatorysequences of the ADH2, GAL4, GAL10, or PHO5 genes, combined with thetranscriptional activation region of a glycolytic enzyme gene such asGAP or PyK. See EP 0 164 556. Furthermore, a yeast promoter may includenaturally occurring promoters of non-yeast origin that have the abilityto bind yeast RNA polymerase and initiate transcription.

Other control elements that may comprise part of the yeast expressionvectors include terminators, for example, from GAPDH or the enolasegenes (Holland et al., J. BIOL. CHEM. (1981) 256:1385). In addition, theorigin of replication from the 2μ plasmid origin is suitable for yeast.A suitable selection gene for use in yeast is the trp1 gene present inthe yeast plasmid. See Tschemper et al., GENE (1980) 10:157; Kingsman etal., GENE (1979) 7:141. The trp1 gene provides a selection marker for amutant strain of yeast lacking the ability to grow in tryptophan.Similarly, Leu2-deficient yeast strains (ATCC 20,622 or 38,626) arecomplemented by known plasmids bearing the Leu2 gene.

Methods of introducing exogenous DNA into yeast hosts are well known tothose of ordinary skill in the art, and typically include, but are notlimited to, either the transformation of spheroplasts or of intact yeasthost cells treated with alkali cations. For example, transformation ofyeast can be carried out according to the method described in Hsiao etal., PROC. NATL. ACAD. SCI. USA (1979) 76:3829 and Van Solingen et al.,J. BACT. (1977) 130:946. However, other methods for introducing DNA intocells such as by nuclear injection, electroporation, or protoplastfusion may also be used as described generally in SAMBROOK ET AL.,MOLECULAR CLONING: A LAB. MANUAL (2001). Yeast host cells may then becultured using standard techniques known to those of ordinary skill inthe art.

Other methods for expressing heterologous proteins in yeast host cellsare well known to those of ordinary skill in the art. See generally U.S.Patent Publication No. 20020055169, U.S. Pat. Nos. 6,361,969; 6,312,923;6,183,985; 6,083,723; 6,017,731; 5,674,706; 5,629,203; 5,602,034; and5,089,398; U.S. Reexamined Patent Nos. RE37,343 and RE35,749; PCTPublished Patent Applications WO 99/078621; WO 98/37208; and WO98/26080; European Patent Applications EP 0 946 736; EP 0 732 403; EP 0480 480; EP 0 460 071; EP 0 340 986; EP 0 329 203; EP 0 324 274; and EP0 164 556. See also Gellissen et al., ANTONIE VAN LEEUWENHOEK (1992)62(1-2):79-93; Romanos et al., YEAST (1992) 8(6):423-488; Goeddel,METHODS IN ENZYMOLOGY (1990) 185:3-7, each incorporated by referenceherein.

The yeast host strains may be grown in fermentors during theamplification stage using standard feed batch fermentation methods wellknown to those of ordinary skill in the art. The fermentation methodsmay be adapted to account for differences in a particular yeast host'scarbon utilization pathway or mode of expression control. For example,fermentation of a Saccharomyces yeast host may require a single glucosefeed, complex nitrogen source (e.g., casein hydrolysates), and multiplevitamin supplementation. In contrast, the methylotrophic yeast P.pastoris may require glycerol, methanol, and trace mineral feeds, butonly simple ammonium (nitrogen) salts for optimal growth and expression.See, e.g., U.S. Pat. No. 5,324,639; Elliott et al., J. PROTEIN CHEM.(1990) 9:95; and Fieschko et al., BIOTECH. BIOENG. (1987) 29:1113,incorporated by reference herein.

Such fermentation methods, however, may have certain common featuresindependent of the yeast host strain employed. For example, a growthlimiting nutrient, typically carbon, may be added to the fermentorduring the amplification phase to allow maximal growth. In addition,fermentation methods generally employ a fermentation medium designed tocontain adequate amounts of carbon, nitrogen, basal salts, phosphorus,and other minor nutrients (vitamins, trace minerals and salts, etc.).Examples of fermentation media suitable for use with Pichia aredescribed in U.S. Pat. Nos. 5,324,639 and 5,231,178, which areincorporated by reference herein.

Baculovirus-Infected Insect Cells The term “insect host” or “insect hostcell” refers to a insect that can be, or has been, used as a recipientfor recombinant vectors or other transfer DNA. The term includes theprogeny of the original insect host cell that has been transfected. Itis understood that the progeny of a single parental cell may notnecessarily be completely identical in morphology or in genomic or totalDNA complement to the original parent, due to accidental or deliberatemutation. Progeny of the parental cell that are sufficiently similar tothe parent to be characterized by the relevant property, such as thepresence of a nucleotide sequence encoding a hGH polypeptide, areincluded in the progeny intended by this definition.

The selection of suitable insect cells for expression of hGHpolypeptides is well known to those of ordinary skill in the art.Several insect species are well described in the art and arecommercially available including Aedes aegypti, Bombyx mori, Drosophilamelanogaster, Spodoptera frugiperda, and Trichoplusia ni. In selectinginsect hosts for expression, suitable hosts may include those shown tohave, inter alia, good secretion capacity, low proteolytic activity, andoverall robustness. Insect are generally available from a variety ofsources including, but not limited to, the Insect Genetic Stock Center,Department of Biophysics and Medical Physics, University of California(Berkeley, Calif.); and the American Type Culture Collection (“ATCC”)(Manassas, Va.).

Generally, the components of a baculovirus-infected insect expressionsystem include a transfer vector, usually a bacterial plasmid, whichcontains both a fragment of the baculovirus genome, and a convenientrestriction site for insertion of the heterologous gene to be expressed;a wild type baculovirus with sequences homologous to thebaculovirus-specific fragment in the transfer vector (this allows forthe homologous recombination of the heterologous gene in to thebaculovirus genome); and appropriate insect host cells and growth media.The materials, methods and techniques used in constructing vectors,transfecting cells, picking plaques, growing cells in culture, and thelike are known in the art and manuals are available describing thesetechniques.

After inserting the heterologous gene into the transfer vector, thevector and the wild type viral genome are transfected into an insecthost cell where the vector and viral genome recombine. The packagedrecombinant virus is expressed and recombinant plaques are identifiedand purified. Materials and methods for baculovirus/insect cellexpression systems are commercially available in kit form from, forexample, Invitrogen Corp. (Carlsbad, Calif.). These techniques aregenerally known to those skilled in the art and fully described inSUMMERS AND SMITH, TEXAS AGRICULTURAL EXPERIMENT STATION BULLETIN NO.1555 (1987), herein incorporated by reference. See also, RICHARDSON, 39METHODS IN MOLECULAR BIOLOGY: BACULOVIRUS EXPRESSION PROTOCOLS (1995);AUSUBEL ET AL., CURRENT PROTOCOLS IN MOLECULAR BIOLOGY 16.9-16.11(1994); KING AND POSSEE, THE BACULOVIRUS SYSTEM: A LABORATORY GUIDE(1992); and O'REILLY ET AL., BACULOVIRUS EXPRESSION VECTORS: ALABORATORY MANUAL (1992).

Indeed, the production of various heterologous proteins usingbaculovirus/insect cell expression systems is well known in the art.See, e.g., U.S. Pat. Nos. 6,368,825; 6,342,216; 6,338,846; 6,261,805;6,245,528, 6,225,060; 6,183,987; 6,168,932; 6,126,944; 6,096,304;6,013,433; 5,965,393; 5,939,285; 5,891,676; 5,871,986; 5,861,279;5,858,368; 5,843,733; 5,762,939; 5,753,220; 5,605,827; 5,583,023;5,571,709; 5,516,657; 5,290,686; WO 02/06305; WO 01/90390; WO 01/27301;WO 01/05956; WO 00/55345; WO 00/20032 WO 99/51721; WO 99/45130; WO99/31257; WO 99/10515; WO 99/09193; WO 97/26332; WO 96/29400; WO96/25496; WO 96/06161; WO 95/20672; WO 93/03173; WO 92/16619; WO92/03628; WO 92/01801; WO 90/14428; WO 90/10078; WO 90/02566; WO90/02186; WO 90/01556; WO 89/01038; WO 89/01037; WO 88/07082, which areincorporated by reference herein.

Vectors that are useful in baculovirus/insect cell expression systemsare known in the art and include, for example, insect expression andtransfer vectors derived from the baculovirus Autographa californicanuclear polyhedrosis virus (AcNPV), which is a helper-independent, viralexpression vector. Viral expression vectors derived from this systemusually use the strong viral polyhedrin gene promoter to driveexpression of heterologous genes. See generally, Reilly ET AL.,BACULOVIRUS EXPRESSION VECTORS: A LABORATORY MANUAL (1992).

Prior to inserting the foreign gene into the baculovirus genome, theabove-described components, comprising a promoter, leader (if desired),coding sequence of interest, and transcription termination sequence, aretypically assembled into an intermediate transplacement construct(transfer vector). Intermediate transplacement constructs are oftenmaintained in a replicon, such as an extra chromosomal element (e.g.,plasmids) capable of stable maintenance in a host, such as bacteria. Thereplicon will have a replication system, thus allowing it to bemaintained in a suitable host for cloning and amplification. Morespecifically, the plasmid may contain the polyhedrin polyadenylationsignal (Miller et al., ANN. REV. MICROBIOL. (1988) 42:177) and aprokaryotic ampicillin-resistance (amp) gene and origin of replicationfor selection and propagation in E. coli.

One commonly used transfer vector for introducing foreign genes intoAcNPV is pAc373. Many other vectors, known to those of skill in the art,have also been designed including, for example, pVL985, which alters thepolyhedrin start codon from ATG to ATT, and which introduces a BamHIcloning site 32 base pairs downstream from the ATT. See Luckow andSummers, 17 VIROLOGY 31 (1989). Other commercially available vectorsinclude, for example, PBlueBac4.5/V5-His; pBlueBacHis2; pMelBac;pBlueBac4.5 (Invitrogen Corp., Carlsbad, Calif.).

After insertion of the heterologous gene, the transfer vector and wildtype baculoviral genome are co-transfected into an insect cell host.Methods for introducing heterologous DNA into the desired site in thebaculovirus virus are known in the art. See SUMMERS AND SMITH, TEXASAGRICULTURAL EXPERIMENT STATION BULLETIN NO. 1555 (1987); Smith et al.,MOL. CELL. BIOL. (1983) 3:2156; Luckow and Summers, VIROLOGY (1989)17:31. For example, the insertion can be into a gene such as thepolyhedrin gene, by homologous double crossover recombination; insertioncan also be into a restriction enzyme site engineered into the desiredbaculovirus gene. See Miller et al., BIOESSAYS (1989)4:91.

Transfection may be accomplished by electroporation. See TROTTER ANDWOOD, 39 METHODS IN MOLECULAR BIOLOGY (1995); Mann and King, J. GEN.VIROL. (1989) 70:3501. Alternatively, liposomes may be used to transfectthe insect cells with the recombinant expression vector and thebaculovirus. See, e.g., Liebman et al., BIOTECHNIQUES (1999) 26(1):36;Graves et al., BIOCHEMISTRY (1998) 37:6050; Nomura et al., J. BIOL.CHEM. (1998) 273(22): 13570; Schmidt et al., PROTEIN EXPRESSION ANDPURIFICATION (1998) 12:323; Siffert et al., NATURE GENETICS (1998)18:45; TILKINS ET AL., CELL BIOLOGY: A LABORATORY HANDBOOK 145-154(1998); Cai et al., PROTEIN EXPRESSION AND PURIFICATION (1997) 10:263;Dolphin et al., NATURE GENETICS (1997) 17:491; Kost et al., GENE (1997)190:139; Jakobsson et al., J. BIOL. CHEM. (1996) 271:22203; Rowles etal., J. BIOL. HEM. (1996) 271(37):22376; Reversey et al., J. BIOL. CHEM.(1996) 271(39):23607-10; Stanley et al., J. BIOL. CHEM. (1995) 270:4121;Sisk et al., J. VIROL. (1994) 68(2):766; and Peng et al., BIOTECHNIQUES(1993) 14.2:274. Commercially available liposomes include, for example,Cellfectin® and Lipofectin® (Invitrogen, Corp., Carlsbad, Calif.). Inaddition, calcium phosphate transfection may be used. See TROTTER ANDWOOD, 39 METHODS IN MOLECULAR BIOLOGY (1995); Kitts, NAR (1990)18(19):5667; and Mann and King, J. GEN. VIROL. (1989) 70:3501.

Baculovirus expression vectors usually contain a baculovirus promoter. Abaculovirus promoter is any DNA sequence capable of binding abaculovirus RNA polymerase and initiating the downstream (3′)transcription of a coding sequence (e.g., structural gene) into mRNA. Apromoter will have a transcription initiation region which is usuallyplaced proximal to the 5′ end of the coding sequence. This transcriptioninitiation region typically includes an RNA polymerase binding site anda transcription initiation site. A baculovirus promoter may also have asecond domain called an enhancer, which, if present, is usually distalto the structural gene. Moreover, expression may be either regulated orconstitutive.

Structural genes, abundantly transcribed at late times in the infectioncycle, provide particularly useful promoter sequences. Examples includesequences derived from the gene encoding the viral polyhedron protein(FRIESEN ET AL., The Regulation of Baculovirus Gene Expression in THEMOLECULAR BIOLOGY OF BACULOVIRUSES (1986); EP 0 127 839 and 0 155 476)and the gene encoding the p10 protein (Vlak et al., J. GEN. VIROL.(1988) 69:765).

The newly formed baculovirus expression vector is packaged into aninfectious recombinant baculovirus and subsequently grown plaques may bepurified by techniques known to those skilled in the art. See Miller etal., BIOESSAYS (1989) 4:91; SUMMERS AND SMITH, TEXAS AGRICULTURALEXPERIMENT STATION BULLETIN NO. 1555 (1987).

Recombinant baculovirus expression vectors have been developed forinfection into several insect cells. For example, recombinantbaculoviruses have been developed for, inter alia, Aedes aegypti (ATCCNo. CCL-125), Bombyx mori (ATCC No. CRL-8910), Drosophila melanogaster(ATCC No. 1963), Spodoptera frugiperda, and Trichoplusia ni. See WO89/046,699; Wright, NATURE (1986) 321:718; Carbonell et al., J. VIROL.(1985) 56:153; Smith et al., MOL. CELL. BIOL. (1983) 3:2156. Seegenerally, Fraser et al., IN VITRO CELL. DEV. BIOL. (1989) 25:225. Morespecifically, the cell lines used for baculovirus expression vectorsystems commonly include, but are not limited to, Sf9 (Spodopterafrugiperda) (ATCC No. CRL-1711), Sf21 (Spodoptera frugiperda)(Invitrogen Corp., Cat. No. 11497-013 (Carlsbad, Calif.)), Tri-368(Trichopulsia ni), and High-Five™ BTI-TN-5B1-4 (Trichopulsia ni).

Cells and culture media are commercially available for both direct andfusion expression of heterologous polypeptides in abaculovirus/expression, and cell culture technology is generally knownto those skilled in the art.

E. Coli and other Prokaryotes Bacterial expression techniques are wellknown in the art. A wide variety of vectors are available for use inbacterial hosts. The vectors may be single copy or low or high multicopyvectors. Vectors may serve for cloning and/or expression. In view of theample literature concerning vectors, commercial availability of manyvectors, and even manuals describing vectors and their restriction mapsand characteristics, no extensive discussion is required here. As iswell-known, the vectors normally involve markers allowing for selection,which markers may provide for cytotoxic agent resistance, prototrophy orimmunity. Frequently, a plurality of markers is present, which providefor different characteristics.

A bacterial promoter is any DNA sequence capable of binding bacterialRNA polymerase and initiating the downstream (3′) transcription of acoding sequence (e.g. structural gene) into mRNA. A promoter will have atranscription initiation region which is usually placed proximal to the5′ end of the coding sequence. This transcription initiation regiontypically includes an RNA polymerase binding site and a transcriptioninitiation site. A bacterial promoter may also have a second domaincalled an operator, that may overlap an adjacent RNA polymerase bindingsite at which RNA synthesis begins. The operator permits negativeregulated (inducible) transcription, as a gene repressor protein maybind the operator and thereby inhibit transcription of a specific gene.Constitutive expression may occur in the absence of negative regulatoryelements, such as the operator. In addition, positive regulation may beachieved by a gene activator protein binding sequence, which, if presentis usually proximal (5′) to the RNA polymerase binding sequence. Anexample of a gene activator protein is the catabolite activator protein(CAP), which helps initiate transcription of the lac operon inEscherichia coli (E. coli) [Raibaud et al., ANNU. REV. GENET. (1984)18:173]. Regulated expression may therefore be either positive ornegative, thereby either enhancing or reducing transcription.

Sequences encoding metabolic pathway enzymes provide particularly usefulpromoter sequences. Examples include promoter sequences derived fromsugar metabolizing enzymes, such as galactose, lactose (lac) [Chang etal., NATURE (1977) 198:1056], and maltose. Additional examples includepromoter sequences derived from biosynthetic enzymes such as tryptophan(trp) [Goeddel et al., NUC. ACIDS RES. (1980) 8:4057; Yelverton et al.,NUCL. ACIDS RES. (1981) 9:731; U.S. Pat. No. 4,738,921; EP Pub. Nos. 036776 and 121 775, which are incorporated by reference herein]. Theβ-galactosidase (bla) promoter system [Weissmann (1981) “The cloning ofinterferon and other mistakes.” In Interferon 3 (Ed. I. Gresser)],bacteriophage lambda PL [Shimatake et al., NATURE (1981) 292:128] and T5[U.S. Pat. No. 4,689,406, which are incorporated by reference herein]promoter systems also provide useful promoter sequences. Preferredmethods of the present invention utilize strong promoters, such as theT7 promoter to induce hGH polypeptides at high levels. Examples of suchvectors are well known in the art and include the pET29 series fromNovagen, and the pPOP vectors described in WO99/05297, which isincorporated by reference herein. Such expression systems produce highlevels of hGH polypeptides in the host without compromising host cellviability or growth parameters.

In addition, synthetic promoters which do not occur in nature alsofunction as bacterial promoters. For example, transcription activationsequences of one bacterial or bacteriophage promoter may be joined withthe operon sequences of another bacterial or bacteriophage promoter,creating a synthetic hybrid promoter [U.S. Pat. No. 4,551,433, which isincorporated by reference herein]. For example, the tac promoter is ahybrid trp-lac promoter comprised of both trp promoter and lac operonsequences that is regulated by the lac repressor [Amann et al., GENE(1983) 25:167; de Boer et al., PROC. NATL. ACAD. SCI. (1983) 80:21].Furthermore, a bacterial promoter can include naturally occurringpromoters of non-bacterial origin that have the ability to bindbacterial RNA polymerase and initiate transcription. A naturallyoccurring promoter of non-bacterial origin can also be coupled with acompatible RNA polymerase to produce high levels of expression of somegenes in prokaryotes. The bacteriophage T7 RNA polymerase/promotersystem is an example of a coupled promoter system [Studier et al., J.MOL. BIOL. (1986) 189:113; Tabor et al., Proc Natl. Acad. Sci. (1985)82:1074]. In addition, a hybrid promoter can also be comprised of abacteriophage promoter and an E. coli operator region (EP Pub. No. 267851).

In addition to a functioning promoter sequence, an efficient ribosomebinding site is also useful for the expression of foreign genes inprokaryotes. In E. coli, the ribosome binding site is called theShine-Dalgarno (SD) sequence and includes an initiation codon (ATG) anda sequence 3-9 nucleotides in length located 3-11 nucleotides upstreamof the initiation codon [Shine et al., NATURE (1975) 254:34]. The SDsequence is thought to promote binding of mRNA to the ribosome by thepairing of bases between the SD sequence and the 3′ and of E. coli 16SrRNA [Steitz et al. “Genetic signals and nucleotide sequences inmessenger RNA”, In Biological Regulation and Development: GeneExpression (Ed. R. F. Goldberger, 1979)]. To express eukaryotic genesand prokaryotic genes with weak ribosome-binding site [Sambrook et al.“Expression of cloned genes in Escherichia coli”, Molecular Cloning: ALaboratory Manual, 1989].

The term “bacterial host” or “bacterial host cell” refers to a bacterialthat can be, or has been, used as a recipient for recombinant vectors orother transfer DNA. The term includes the progeny of the originalbacterial host cell that has been transfected. It is understood that theprogeny of a single parental cell may not necessarily be completelyidentical in morphology or in genomic or total DNA complement to theoriginal parent, due to accidental or deliberate mutation. Progeny ofthe parental cell that are sufficiently similar to the parent to becharacterized by the relevant property, such as the presence of anucleotide sequence encoding a hGH polypeptide, are included in theprogeny intended by this definition.

The selection of suitable host bacteria for expression of hGHpolypeptides is well known to those of ordinary skill in the art. Inselecting bacterial hosts for expression, suitable hosts may includethose shown to have, inter alia, good inclusion body formation capacity,low proteolytic activity, and overall robustness. Bacterial hosts aregenerally available from a variety of sources including, but not limitedto, the Bacterial Genetic Stock Center, Department of Biophysics andMedical Physics, University of California (Berkeley, Calif.); and theAmerican Type Culture Collection (“ATCC”) (Manassas, Va.).Industrial/pharmaceutical fermentation generally use bacterial derivedfrom K strains (e.g. W3110) or from bacteria derived from B strains(e.g. BL21). These strains are particularly useful because their growthparameters are extremely well known and robust. In addition, thesestrains are non-pathogenic, which is commercially important for safetyand environmental reasons. In one embodiment of the methods of thepresent invention, the E. coli host is a strain of BL21. In anotherembodiment of the methods of the present invention, the E. coli host isa protease minus strain including, but not limited to, OMP- and LON-. Inanother embodiment of the methods of the present invention, the hostcell strain is a species of Pseudomonas, including but not limited to,Pseudomonas fluorescens, Pseudomonas aeruginosa, and Pseudomonas putida.Pseudomonas fluorescens biovar 1, designated strain MB101, is availablefor therapeutic protein production processes by The Dow Chemical Companyas a host strain (Midland, Mich. available on the World Wide Web atdow.com). U.S. Pat. Nos. 4,755,465 and 4,859,600, which are incorporatedherein, describes the use of Pseudomonas strains as a host cell for hGHproduction.

Once a recombinant host cell strain has been established (i.e., theexpression construct has been introduced into the host cell and hostcells with the proper expression construct are isolated), therecombinant host cell strain is cultured under conditions appropriatefor production of hGH polypeptides. As will be apparent to one of skillin the art, the method of culture of the recombinant host cell strainwill be dependent on the nature of the expression construct utilized andthe identity of the host cell. Recombinant host strains are normallycultured using methods that are well known to the art. Recombinant hostcells are typically cultured in liquid medium containing assimilatablesources of carbon, nitrogen, and inorganic salts and, optionally,containing vitamins, amino acids, growth factors, and otherproteinaceous culture supplements well known to the art. Liquid mediafor culture of host cells may optionally contain antibiotics oranti-fungals to prevent the growth of undesirable microorganisms and/orcompounds including, but not limited to, antibiotics to select for hostcells containing the expression vector.

Recombinant host cells may be cultured in batch or continuous formats,with either cell harvesting (in the case where the hGH polypeptideaccumulates intracellularly) or harvesting of culture supernatant ineither batch or continuous formats. For production in prokaryotic hostcells, batch culture and cell harvest are preferred.

The hGH polypeptides of the present invention are normally purifiedafter expression in recombinant systems. The hGH polypeptide may bepurified from host cells by a variety of methods known to the art.Normally, hGH polypeptides produced in bacterial host cells is poorlysoluble or insoluble (in the form of inclusion bodies). In oneembodiment of the present invention, amino acid substitutions mayreadily be made in the hGH polypeptide that are selected for the purposeof increasing the solubility of the recombinantly produced proteinutilizing the methods disclosed herein as well as those known in theart. In the case of insoluble protein, the protein may be collected fromhost cell lysates by centrifugation and may further be followed byhomogenization of the cells. In the case of poorly soluble protein,compounds including, but not limited to, polyethylene imine (PEI) may beadded to induce the precipitation of partially soluble protein. Theprecipitated protein may then be conveniently collected bycentrifugation. Recombinant host cells may be disrupted or homogenizedto release the inclusion bodies from within the cells using a variety ofmethods well known to those of ordinary skill in the art. Host celldisruption or homogenization may be performed using well knowntechniques including, but not limited to, enzymatic cell disruption,sonication, dounce homogenization, or high pressure release disruption.In one embodiment of the method of the present invention, the highpressure release technique is used to disrupt the E. coli host cells torelease the inclusion bodies of the hGH polypeptides. It has been foundthat yields of insoluble hGH polypeptide in the form of inclusion bodiesmay be increased by utilizing only one passage of the E. coli host cellsthrough the homogenizer. When handling inclusion bodies of hGHpolypeptide, it is advantageous to minimize the homogenization time onrepetitions in order to maximize the yield of inclusion bodies withoutloss due to factors such as solubilization, mechanical shearing orproteolysis.

Insoluble or precipitated hGH polypeptide may then be solubilized usingany of a number of suitable solubilization agents known to the art.Preferably, the hGH polypeptide is solubilized with urea or guanidinehydrochloride. The volume of the solubilized hGH polypeptide-BP shouldbe minimized so that large batches may be produced using convenientlymanageable batch sizes. This factor may be significant in a large-scalecommercial setting where the recombinant host may be grown in batchesthat are thousands of liters in volume. In addition, when manufacturinghGH polypeptide in a large-scale commercial setting, in particular forhuman pharmaceutical uses, the avoidance of harsh chemicals that candamage the machinery and container, or the protein product itself,should be avoided, if possible. It has been shown in the method of thepresent invention that the milder denaturing agent urea can be used tosolubilize the hGH polypeptide inclusion bodies in place of the harsherdenaturing agent guanidine hydrochloride. The use of urea significantlyreduces the risk of damage to stainless steel equipment utilized in themanufacturing and purification process of hGH polypeptide whileefficiently solubilizing the hGH polypeptide inclusion bodies.

When hGH polypeptide is produced as a fusion protein, the fusionsequence is preferably removed. Removal of a fusion sequence may beaccomplished by enzymatic or chemical cleavage, preferably by enzymaticcleavage. Enzymatic removal of fusion sequences may be accomplishedusing methods well known to those in the art. The choice of enzyme forremoval of the fusion sequence will be determined by the identity of thefusion, and the reaction conditions will be specified by the choice ofenzyme as will be apparent to one skilled in the art. The cleaved hGHpolypeptide is preferably purified from the cleaved fusion sequence bywell known methods. Such methods will be determined by the identity andproperties of the fusion sequence and the hGH polypeptide, as will beapparent to one skilled in the art. Methods for purification mayinclude, but are not limited to, size-exclusion chromatography,hydrophobic interaction chromatography, ion-exchange chromatography ordialysis or any combination thereof.

The hGH polypeptide is also preferably purified to remove DNA from theprotein solution. DNA may be removed by any suitable method known to theart, such as precipitation or ion exchange chromatography, but ispreferably removed by precipitation with a nucleic acid precipitatingagent, such as, but not limited to, protamine sulfate. The hGHpolypeptide may be separated from the precipitated DNA using standardwell known methods including, but not limited to, centrifugation orfiltration. Removal of host nucleic acid molecules is an importantfactor in a setting where the hGH polypeptide is to be used to treathumans and the methods of the present invention reduce host cell DNA topharmaceutically acceptable levels.

Methods for small-scale or large-scale fermentation can also be used inprotein expression, including but not limited to, fermentors, shakeflasks, fluidized bed bioreactors, hollow fiber bioreactors, rollerbottle culture systems, and stirred tank bioreactor systems. Each ofthese methods can be performed in a batch, fed-batch, or continuous modeprocess.

Human hGH polypeptides of the invention can generally be recovered usingmethods standard in the art. For example, culture medium or cell lysatecan be centrifuged or filtered to remove cellular debris. Thesupernatant may be concentrated or diluted to a desired volume ordiafiltered into a suitable buffer to condition the preparation forfurther purification. Further purification of the hGH polypeptide of thepresent invention include separating deamidated and clipped forms of thehGH polypeptide variant from the intact form.

Any of the following exemplary procedures can be employed forpurification of hGH polypeptides of the invention: affinitychromatography; anion- or cation-exchange chromatography (using,including but not limited to, DEAE SEPHAROSE); chromatography on silica;reverse phase HPLC; gel filtration (using, including but not limited to,SEPHADEX G-75); hydrophobic interaction chromatography; size-exclusionchromatography, metal-chelate chromatography;ultrafiltration/diafiltration; ethanol precipitation; ammonium sulfateprecipitation; chromatofocusing; displacement chromatography;electrophoretic procedures (including but not limited to preparativeisoelectric focusing), differential solubility (including but notlimited to ammonium sulfate precipitation), SDS-PAGE, or extraction.

Proteins of the present invention, including but not limited to,proteins comprising unnatural amino acids, antibodies to proteinscomprising unnatural amino acids, binding partners for proteinscomprising unnatural amino acids, etc., can be purified, eitherpartially or substantially to homogeneity, according to standardprocedures known to and used by those of skill in the art. Accordingly,polypeptides of the invention can be recovered and purified by any of anumber of methods well known in the art, including but not limited to,ammonium sulfate or ethanol precipitation, acid or base extraction,column chromatography, affinity column chromatography, anion or cationexchange chromatography, phosphocellulose chromatography, hydrophobicinteraction chromatography, hydroxylapatite chromatography, lectinchromatography, gel electrophoresis and the like. Protein refoldingsteps can be used, as desired, in making correctly folded matureproteins. High performance liquid chromatography (HPLC), affinitychromatography or other suitable methods can be employed in finalpurification steps where high purity is desired. In one embodiment,antibodies made against unnatural amino acids (or proteins comprisingunnatural amino acids) are used as purification reagents, including butnot limited to, for affinity-based purification of proteins comprisingone or more unnatural amino acid(s). Once purified, partially or tohomogeneity, as desired, the polypeptides are optionally used for a widevariety of utilities, including but not limited to, as assay components,therapeutics, prophylaxis, diagnostics, research reagents, and/or asimmunogens for antibody production.

In addition to other references noted herein, a variety ofpurification/protein folding methods are well known in the art,including, but not limited to, those set forth in R. Scopes, ProteinPurification, Springer-Verlag, N.Y. (1982); Deutscher, Methods inEnzymology Vol. 182: Guide to Protein Purification, Academic Press, Inc.N.Y. (1990); Sandana, (1997) Bioseparation of Proteins, Academic Press,Inc.; Bollag et al. (1996) Protein Methods, 2nd Edition Wiley-Liss, NY;Walker, (1996) The Protein Protocols Handbook Humana Press, NJ, Harrisand Angal, (1990) Protein Purification Applications: A PracticalApproach IRL Press at Oxford, Oxford, England; Harris and Angal, ProteinPurification Methods: A Practical Approach IRL Press at Oxford, Oxford,England; Scopes, (1993) Protein Purification: Principles and Practice3rd Edition Springer Verlag, NY; Janson and Ryden, (1998) ProteinPurification: Principles, High Resolution Methods and Applications,Second Edition Wiley-VCH, NY; and Walker (1998), Protein Protocols onCD-ROM Humana Press, NJ; and the references cited therein.

One advantage of producing a protein or polypeptide of interest with anunnatural amino acid in a eukaryotic host cell or non-eukaryotic hostcell is that typically the proteins or polypeptides will be folded intheir native conformations. However, in certain embodiments of theinvention, those of skill in the art will recognize that, aftersynthesis, expression and/or purification, proteins can possess aconformation different from the desired conformations of the relevantpolypeptides. In one aspect of the invention, the expressed protein isoptionally denatured and then renatured. This is accomplished utilizingmethods known in the art, including but not limited to, by adding achaperonin to the protein or polypeptide of interest, by solubilizingthe proteins in a chaotropic agent such as guanidine HCl, utilizingprotein disulfide isomerase, etc.

In general, it is occasionally desirable to denature and reduceexpressed polypeptides and then to cause the polypeptides to re-foldinto the preferred conformation. For example, guanidine, urea, DTT, DTE,and/or a chaperonin can be added to a translation product of interest.Methods of reducing, denaturing and renaturing proteins are well knownto those of skill in the art (see, the references above, and Debinski,et al. (1993) J. Biol. Chem., 268: 14065-14070; Kreitman and Pastan(1993) Bioconjug. Chem., 4: 581-585; and Buchner, et al., (1992) Anal.Biochem., 205: 263-270). Debinski, et al., for example, describe thedenaturation and reduction of inclusion body proteins in guanidine-DTE.The proteins can be refolded in a redox buffer containing, including butnot limited to, oxidized glutathione and L-arginine. Refolding reagentscan be flowed or otherwise moved into contact with the one or morepolypeptide or other expression product, or vice-versa.

In the case of prokaryotic production of hGH polypeptide, the hGHpolypeptide thus produced may be misfolded and thus lacks or has reducedbiological activity. The bioactivity of the protein may be restored by“refolding”. In general, misfolded hGH polypeptide is refolded bysolubilizing (where the hGH polypeptide is also insoluble), unfoldingand reducing the polypeptide chain using, for example, one or morechaotropic agents (e.g. urea and/or guanidine) and a reducing agentcapable of reducing disulfide bonds (e.g. dithiothreitol, DTT or2-mercaptoethanol, 2-ME). At a moderate concentration of chaotrope, anoxidizing agent is then added (e.g., oxygen, cystine or cystamine),which allows the reformation of disulfide bonds. hGH polypeptide may berefolded using standard methods known in the art, such as thosedescribed in U.S. Pat. Nos. 4,511,502, 4,511,503, and 4,512,922, whichare incorporated by reference herein. The hGH polypeptide may also becofolded with other proteins to form heterodimers or heteromultimers.After refolding or cofolding, the hGH polypeptide is preferably furtherpurified.

General Purification Methods Any one of a variety of isolation steps maybe performed on the cell lysate comprising hGH polypeptide or on any hGHpolypeptide mixtures resulting from any isolation steps including, butnot limited to, affinity chromatography, ion exchange chromatography,hydrophobic interaction chromatography, gel filtration chromatography,high performance liquid chromatography (“HPLC”), reversed phase-HPLC(“RP-HPLC”), expanded bed adsorption, or any combination and/orrepetition thereof and in any appropriate order.

Equipment and other necessary materials used in performing thetechniques described herein are commercially available. Pumps, fractioncollectors, monitors, recorders, and entire systems are available from,for example, Applied Biosystems (Foster City, Calif.), Bio-RadLaboratories, Inc. (Hercules, Calif.), and Amersham Biosciences, Inc.(Piscataway, N.J.). Chromatographic materials including, but not limitedto, exchange matrix materials, media, and buffers are also availablefrom such companies.

Equilibration, and other steps in the column chromatography processesdescribed herein such as washing and elution, may be more rapidlyaccomplished using specialized equipment such as a pump. Commerciallyavailable pumps include, but are not limited to, HILOAD® Pump P-50,Peristaltic Pump P-1, Pump P-901, and Pump P-903 (Amersham Biosciences,Piscataway, N.J.).

Examples of fraction collectors include RediFrac Fraction Collector,FRAC-100 and FRAC-200 Fraction Collectors, and SUPERFRAC® FractionCollector (Amersham Biosciences, Piscataway, N.J.). Mixers are alsoavailable to form pH and linear concentration gradients. Commerciallyavailable mixers include Gradient Mixer GM-1 and In-Line Mixers(Amersham Biosciences, Piscataway, N.J.).

The chromatographic process may be monitored using any commerciallyavailable monitor. Such monitors may be used to gather information likeUV, pH, and conductivity. Examples of detectors include Monitor UV-1,UVICORD® S II, Monitor UV-M II, Monitor UV-900, Monitor UPC-900, MonitorpH/C-900, and Conductivity Monitor (Amersham Biosciences, Piscataway,N.J.). Indeed, entire systems are commercially available including thevarious AKTA® systems from Amersham Biosciences (Piscataway, N.J.).

In one embodiment of the present invention, for example, the hGHpolypeptide may be reduced and denatured by first denaturing theresultant purified hGH polypeptide in urea, followed by dilution intoTRIS buffer containing a reducing agent (such as DTT) at a suitable pH.In another embodiment, the hGH polypeptide is denatured in urea in aconcentration range of between about 2 M to about 9 M, followed bydilution in TRIS buffer at a pH in the range of about 5.0 to about 8.0.The refolding mixture of this embodiment may then be incubated. In oneembodiment, the refolding mixture is incubated at room temperature forfour to twenty-four hours. The reduced and denatured hGH polypeptidemixture may then be further isolated or purified.

As stated herein, the pH of the first hGH polypeptide mixture may beadjusted prior to performing any subsequent isolation steps. Inaddition, the first hGH polypeptide mixture or any subsequent mixturethereof may be concentrated using techniques known in the art. Moreover,the elution buffer comprising the first hGH polypeptide mixture or anysubsequent mixture thereof may be exchanged for a buffer suitable forthe next isolation step using techniques well known to those of ordinaryskill in the art.

Ion Exchange Chromatography In one embodiment, and as an optional,additional step, ion exchange chromatography may be performed on thefirst hGH polypeptide mixture. See generally ION EXCHANGECHROMATOGRAPHY: PRINCIPLES AND METHODS (Cat. No. 18-1114-21, AmershamBiosciences (Piscataway, N.J.)). Commercially available ion exchangecolumns include HITRAP®, HIPREP®, and HILOAD® Columns (AmershamBiosciences, Piscataway, N.J.). Such columns utilize strong anionexchangers such as Q SEPHAROSE® Fast Flow, Q SEPHAROSE® HighPerformance, and Q SEPHAROSE® XL; strong cation exchangers such as SPSEPHAROSE® High Performance, SP SEPHAROSE® Fast Flow, and SP SEPHAROSE®XL; weak anion exchangers such as DEAE SEPHAROSE® Fast Flow; and weakcation exchangers such as CM SEPHAROSE® Fast Flow (Amersham Biosciences,Piscataway, N.J.). Cation exchange column chromatography may beperformed on the hGH polypeptide at any stage of the purificationprocess to isolate substantially purified hGH polypeptide. The cationexchange chromatography step may be performed using any suitable cationexchange matrix. Useful cation exchange matrices include, but are notlimited to, fibrous, porous, non-porous, microgranular, beaded, orcross-linked cation exchange matrix materials. Such cation exchangematrix materials include, but are not limited to, cellulose, agarose,dextran, polyacrylate, polyvinyl, polystyrene, silica, polyether, orcomposites of any of the foregoing. Following adsorption of the hGHpolypeptide to the cation exchanger matrix, substantially purified hGHpolypeptide may be eluted by contacting the matrix with a buffer havinga sufficiently high pH or ionic strength to displace the hGH polypeptidefrom the matrix. Suitable buffers for use in high pH elution ofsubstantially purified hGH polypeptide include, but are not limited to,citrate, phosphate, formate, acetate, HEPES, and MES buffers ranging inconcentration from at least about 5 mM to at least about 100 mM.

Reverse-Phase Chromatography RP-HPLC may be performed to purify proteinsfollowing suitable protocols that are known to those of ordinary skillin the art. See, e.g., Pearson et al., ANAL BIOCHEM. (1982) 124:217-230(1982); Rivier et al., J. CHROM. (1983) 268:112-119; Kunitani et al., J.CHROM. (1986) 359:391-402. RP-HPLC may be performed on the hGHpolypeptide to isolate substantially purified hGH polypeptide. In thisregard, silica derivatized resins with alkyl functionalities with a widevariety of lengths, including, but not limited to, at least about C₃ toat least about C₃₀, at least about C₃ to at least about C₂₀, or at leastabout C₃ to at least about C₁₈, resins may be used. Alternatively, apolymeric resin may be used. For example, TosoHaas Amberchrome CG 1000sdresin may be used, which is a styrene polymer resin. Cyano or polymericresins with a wide variety of alkyl chain lengths may also be used.Furthermore, the RP-HPLC column may be washed with a solvent such asethanol. A suitable elution buffer containing an ion pairing agent andan organic modifier such as methanol, isopropanol, tetrahydrofuran,acetonitrile or ethanol, may be used to elute the hGH polypeptide fromthe RP-HPLC column. The most commonly used ion pairing agents include,but are not limited to, acetic acid, formic acid, perchloric acid,phosphoric acid, trifluoroacetic acid, heptafluorobutyric acid,triethylamine, tetramethylammonium, tetrabutylammonium, triethylammoniumacetate. Elution may be performed using one or more gradients orisocratic conditions, with gradient conditions preferred to reduce theseparation time and to decrease peak width. Another method involves theuse of two gradients with different solvent concentration ranges.Examples of suitable elution buffers for use herein may include, but arenot limited to, ammonium acetate and acetonitrile solutions.

Hydrophobic Interaction Chromatography Purification TechniquesHydrophobic interaction chromatography (HIC) may be performed on the hGHpolypeptide. See generally HYDROPHOBIC INTERACTION CHROMATOGRAPHYHANDBOOK: PRINCIPLES AND METHODS (Cat. No. 18-1020-90, AmershamBiosciences (Piscataway, N.J.) which is incorporated by referenceherein. Suitable HIC matrices may include, but are not limited to,alkyl- or aryl-substituted matrices, such as butyl-, hexyl-, octyl- orphenyl-substituted matrices including agarose, cross-linked agarose,sepharose, cellulose, silica, dextran, polystyrene, poly(methacrylate)matrices, and mixed mode resins, including but not limited to, apolyethyleneamine resin or a butyl- or phenyl-substitutedpoly(methacrylate) matrix. Commercially available sources forhydrophobic interaction column chromatography include, but are notlimited to, HITRAP®, HIPREP®, and HILOAD® columns (Amersham Biosciences,Piscataway, N.J.). Briefly, prior to loading, the HIC column may beequilibrated using standard buffers known to those of ordinary skill inthe art, such as an acetic acid/sodium chloride solution or HEPEScontaining ammonium sulfate. After loading the hGH polypeptide, thecolumn may then washed using standard buffers and conditions to removeunwanted materials but retaining the hGH polypeptide on the HIC column.The hGH polypeptide may be eluted with about 3 to about 10 columnvolumes of a standard buffer, such as a HEPES buffer containing EDTA andlower ammonium sulfate concentration than the equilibrating buffer, oran acetic acid/sodium chloride buffer, among others. A decreasing linearsalt gradient using, for example, a gradient of potassium phosphate, mayalso be used to elute the hGH molecules. The eluant may then beconcentrated, for example, by filtration such as diafiltration orultrafiltration. Diafiltration may be utilized to remove the salt usedto elute the hGH polypeptide.

Other Purification Techniques Yet another isolation step using, forexample, gel filtration (GEL FILTRATION: PRINCIPLES AND METHODS (Cat.No. 18-1022-18, Amersham Biosciences, Piscataway, N.J.) which isincorporated by reference herein, HPLC, expanded bed adsorption,ultrafiltration, diafiltration, lyophilization, and the like, may beperformed on the first hGH polypeptide mixture or any subsequent mixturethereof, to remove any excess salts and to replace the buffer with asuitable buffer for the next isolation step or even formulation of thefinal drug product. The yield of hGH polypeptide, includingsubstantially purified hGH polypeptide, may be monitored at each stepdescribed herein using techniques known to those of ordinary skill inthe art. Such techniques may also used to assess the yield ofsubstantially purified hGH polypeptide following the last isolationstep. For example, the yield of hGH polypeptide may be monitored usingany of several reverse phase high pressure liquid chromatographycolumns, having a variety of alkyl chain lengths such as cyano RP-HPLC,C₁₈RP-HPLC; as well as cation exchange HPLC and gel filtration HPLC.

Purity may be determined using standard techniques, such as SDS-PAGE, orby measuring hGH polypeptide using Western blot and ELISA assays. Forexample, polyclonal antibodies may be generated against proteinsisolated from negative control yeast fermentation and the cationexchange recovery. The antibodies may also be used to probe for thepresence of contaminating host cell proteins.

RP-HPLC material Vydac C4 (Vydac) consists of silica gel particles, thesurfaces of which carry C4-alkyl chains. The separation of hGHpolypeptide from the proteinaceous impurities is based on differences inthe strength of hydrophobic interactions. Elution is performed with anacetonitrile gradient in diluted trifluoroacetic acid. Preparative HPLCis performed using a stainless steel column (filled with 2.8 to 3.2liter of Vydac C4 silicagel). The Hydroxyapatite Ultrogel eluate isacidified by adding trifluoroacetic acid and loaded onto the Vydac C4column. For washing and elution an acetonitrile gradient in dilutedtrifluoroacetic acid is used. Fractions are collected and immediatelyneutralized with phosphate buffer. The hGH polypeptide fractions whichare within the IPC limits are pooled.

DEAE Sepharose (Pharmacia) material consists of diethylaminoethyl(DEAE)-groups which are covalently bound to the surface of Sepharosebeads. The binding of hGH polypeptide to the DEAE groups is mediated byionic interactions. Acetonitrile and trifluoroacetic acid pass throughthe column without being retained. After these substances have beenwashed off, trace impurities are removed by washing the column withacetate buffer at a low pH. Then the column is washed with neutralphosphate buffer and hGH polypeptide is eluted with a buffer withincreased ionic strength. The column is packed with DEAE Sepharose fastflow. The column volume is adjusted to assure a hGH polypeptide load inthe range of 3-10 mg hGH polypeptide/ml gel. The column is washed withwater and equilibration buffer (sodium/potassium phosphate). The pooledfractions of the HPLC eluate are loaded and the column is washed withequilibration buffer. Then the column is washed with washing buffer(sodium acetate buffer) followed by washing with equilibration buffer.Subsequently, hGH polypeptide is eluted from the column with elutionbuffer (sodium chloride, sodium/potassium phosphate) and collected in asingle fraction in accordance with the master elution profile. Theeluate of the DEAE Sepharose column is adjusted to the specifiedconductivity. The resulting drug substance is sterile filtered intoTeflon bottles and stored at −70° C.

A wide variety of methods and procedures can be used to assess the yieldand purity of a hGH protein one or more non-naturally encoded aminoacids, including but not limited to, the Bradford assay, SDS-PAGE,silver stained SDS-PAGE, coomassie stained SDS-PAGE, mass spectrometry(including but not limited to, MALDI-TOF) and other methods forcharacterizing proteins known to one skilled in the art.

VIII. Expression in Alternate Systems

Several strategies have been employed to introduce unnatural amino acidsinto proteins in non-recombinant host cells, mutagenized host cells, orin cell-free systems. These systems are also suitable for use in makingthe hGH polypeptides of the present invention. Derivatization of aminoacids with reactive side-chains such as Lys, Cys and Tyr resulted in theconversion of lysine to N²-acetyl-lysine. Chemical synthesis alsoprovides a straightforward method to incorporate unnatural amino acids.With the recent development of enzymatic ligation and native chemicalligation of peptide fragments, it is possible to make larger proteins.See, e.g., P. E. Dawson and S. B. H. Kent, Annu. Rev. Biochem., 69:923(2000). A general in vitro biosynthetic method in which a suppressortRNA chemically acylated with the desired unnatural amino acid is addedto an in vitro extract capable of supporting protein biosynthesis, hasbeen used to site-specifically incorporate over 100 unnatural aminoacids into a variety of proteins of virtually any size. See, e.g., V. W.Cornish, D. Mendel and P. G. Schultz, Angew. Chem. Int. Ed. Engl., 1995,34:621 (1995); C. J. Noren, S. J. Anthony-Cahill, M. C. Griffith, P. G.Schultz, A general method for site-specific incorporation of unnaturalamino acids into proteins, Science 244:182-188 (1989); and, J. D. Bain,C. G. Glabe, T. A. Dix, A. R. Chamberlin, E. S. Diala, Biosyntheticsite-specific incorporation of a non-natural amino acid into apolypeptide, J. Am. Chem. Soc. 111:8013-8014 (1989). A broad range offunctional groups has been introduced into proteins for studies ofprotein stability, protein folding, enzyme mechanism, and signaltransduction.

An in vivo method, termed selective pressure incorporation, wasdeveloped to exploit the promiscuity of wild-type synthetases. See,e.g., N. Budisa, C. Minks, S. Alefelder, W. Wenger, F. M. Dong, L.Moroder and R. Huber, FASEB J., 13:41 (1999). An auxotrophic strain, inwhich the relevant metabolic pathway supplying the cell with aparticular natural amino acid is switched off, is grown in minimal mediacontaining limited concentrations of the natural amino acid, whiletranscription of the target gene is repressed. At the onset of astationary growth phase, the natural amino acid is depleted and replacedwith the unnatural amino acid analog. Induction of expression of therecombinant protein results in the accumulation of a protein containingthe unnatural analog. For example, using this strategy, o, m andp-fluorophenylalanines have been incorporated into proteins, and exhibittwo characteristic shoulders in the UV spectrum which can be easilyidentified, see, e.g., C. Minks, R. Huber, L. Moroder and N. Budisa,Anal. Biochem., 284:29 (2000); trifluoromethionine has been used toreplace methionine in bacteriophage T4 lysozyme to study its interactionwith chitooligosaccharide ligands by ¹⁹F NMR, see, e.g., H. Duewel, E.Daub, V. Robinson and J. F. Honek, Biochemistry, 36:3404 (1997); andtrifluoroleucine has been incorporated in place of leucine, resulting inincreased thermal and chemical stability of a leucine-zipper protein.See, e.g., Y. Tang, G. Ghirlanda, W. A. Petka, T. Nakajima, W. F.DeGrado and D. A. Tirrell, Angew. Chem. Int. Ed. Engl., 40:1494 (2001).Moreover, selenomethionine and telluromethionine are incorporated intovarious recombinant proteins to facilitate the solution of phases inX-ray crystallography. See, e.g., W. A. Hendrickson, J. R. Horton and D.M. Lemaster, EMBO J., 9:1665 (1990); J. O. Boles, K. Lewinski, M.Kunkle, J. D. Odom, B. Dunlap, L. Lebioda and M. Hatada, Nat. Struct.Biol., 1:283 (1994); N. Budisa, B. Steipe, P. Demange, C. Eckerskorn, J.Kellermann and R. Huber, Eur. J. Biochem., 230:788 (1995); and, N.Budisa, W. Karnbrock, S. Steinbacher, A. Humm, L. Prade, T. Neuefeind,L. Moroder and R. Huber, J. Mol. Biol., 270:616 (1997). Methionineanalogs with alkene or alkyne functionalities have also beenincorporated efficiently, allowing for additional modification ofproteins by chemical means. See, e.g., J. C. M. vanHest and D. A.Tirrell, FEBS Lett., 428:68 (1998); J. C. M. van Hest, K. L. Kiick andD. A. Tirrell, J. Am. Chem. Soc., 122:1282 (2000); and, K. L. Kiick andD. A. Tirrell, Tetrahedron, 56:9487 (2000); U.S. Pat. No. 6,586,207;U.S. Patent Publication 2002/0042097, which are incorporated byreference herein.

The success of this method depends on the recognition of the unnaturalamino acid analogs by aminoacyl-tRNA synthetases, which, in general,require high selectivity to insure the fidelity of protein translation.One way to expand the scope of this method is to relax the substratespecificity of aminoacyl-tRNA synthetases, which has been achieved in alimited number of cases. For example, replacement of Ala²⁹⁴ by Gly inEscherichia coli phenylalanyl-tRNA synthetase (PheRS) increases the sizeof substrate binding pocket, and results in the acylation of tRNAPhe byp-Cl-phenylalanine (p-Cl-Phe). See, M. Ibba, P. Kast and H. Hennecke,Biochemistry, 33:7107 (1994). An Escherichia coli strain harboring thismutant PheRS allows the incorporation of p-Cl-phenylalanine orp-Br-phenylalanine in place of phenylalanine. See, e.g., M. Ibba and H.Hennecke, FEBS Lett., 364:272 (1995); and, N. Sharma, R. Furter, P. Kastand D. A. Tirrell, FEBS Lett., 467:37 (2000). Similarly, a pointmutation Phe130Ser near the amino acid binding site of Escherichia colityrosyl-tRNA synthetase was shown to allow azatyrosine to beincorporated more efficiently than tyrosine. See, F. Hamano-Takaku, T.Iwama, S. Saito-Yano, K. Takaku, Y. Monden, M. Kitabatake, D. Soll andS. Nishimura, J. Biol. Chem., 275:40324 (2000).

Another strategy to incorporate unnatural amino acids into proteins invivo is to modify synthetases that have proofreading mechanisms. Thesesynthetases cannot discriminate and therefore activate amino acids thatare structurally similar to the cognate natural amino acids. This erroris corrected at a separate site, which deacylates the mischarged aminoacid from the tRNA to maintain the fidelity of protein translation. Ifthe proofreading activity of the synthetase is disabled, structuralanalogs that are misactivated may escape the editing function and beincorporated. This approach has been demonstrated recently with thevalyl-tRNA synthetase (ValRS). See, V. Doring, H. D. Mootz, L. A.Nangle, T. L. Hendrickson, V. de Crecy-Lagard, P. Schimmel and P.Marliere, Science, 292:501 (2001). ValRS can misaminoacylate tRNAValwith Cys, Thr, or aminobutyrate (Abu); these noncognate amino acids aresubsequently hydrolyzed by the editing domain. After random mutagenesisof the Escherichia coli chromosome, a mutant Escherichia coli strain wasselected that has a mutation in the editing site of ValRS. Thisedit-defective ValRS incorrectly charges tRNAVal with Cys. Because Abusterically resembles Cys (—SH group of Cys is replaced with —CH3 inAbu), the mutant ValRS also incorporates Abu into proteins when thismutant Escherichia coli strain is grown in the presence of Abu. Massspectrometric analysis shows that about 24% of valines are replaced byAbu at each valine position in the native protein.

Solid-phase synthesis and semisynthetic methods have also allowed forthe synthesis of a number of proteins containing novel amino acids. Forexample, see the following publications and references cited within,which are as follows: Crick, F. J. C., Barrett, L. Brenner, S.Watts-Tobin, R. General nature of the genetic code for proteins. Nature,192:1227-1232 (1961); Hofmann, K., Bohn, H. Studies on polypeptides.XXXVI. The effect of pyrazole-imidazole replacements on the S-proteinactivating potency of an S-peptide fragment, J. Am. Chem,88(24):5914-5919 (1966); Kaiser, E. T. Synthetic approaches tobiologically active peptides and proteins including enyzmes, Acc ChemRes, 47-54 (1989); Nakatsuka, T., Sasaki, T., Kaiser, E. T. Peptidesegment coupling catalyzed by the semisynthetic enzyme thiosubtilisin, JAm Chem Soc, 3808-3810 (1987); Schnolzer, M., Kent, S B H. Constructingproteins by dovetailing unprotected synthetic peptides:backbone-engineered HIV protease, Science, 256(5054):221-225 (1992);Chaiken, I. M. Semisynthetic peptides and proteins, CRC Crit RevBiochem, 11(3):255-301 (1981); Offord, R. E. Protein engineering bychemical means? Protein Eng., 1(3):151-157 (1987); and, Jackson, D. Y.,Burnier, J., Quan, C., Stanley, M., Tom, J., Wells, J. A. A DesignedPeptide Ligase for Total Synthesis of Ribonuclease A with UnnaturalCatalytic Residues, Science, 266(5183):243 (1994).

Chemical modification has been used to introduce a variety of unnaturalside chains, including cofactors, spin labels and oligonucleotides intoproteins in vitro. See, e.g., Corey, D. R., Schultz, P. G. Generation ofa hybrid sequence-specific single-stranded deoxyribonuclease, Science,238(4832):1401-1403 (1987); Kaiser, E. T., Lawrence D. S., Rokita, S. E.The chemical modification of enzymatic specificity, Annu Rev Biochem,54:565-595 (1985); Kaiser, E. T., Lawrence, D. S. Chemical mutation ofenzyme active sites, Science, 226(4674):505-511 (1984); Neet, K. E.,Nanci A, Koshland, D. E. Properties of thiol-subtilisin, J Biol. Chem,243(24):6392-6401 (1968); Polgar, L. B., M. L. A new enzyme containing asynthetically formed active site. Thiol-subtilisin. J. Am Chem Soc,3153-3154 (1966); and, Pollack, S. J., Nakayama, G. Schultz, P. G.Introduction of nucleophiles and spectroscopic probes into antibodycombining sites, Science, 242(4881):1038-1040 (1988).

Alternatively, biosynthetic methods that employ chemically modifiedaminoacyl-tRNAs have been used to incorporate several biophysical probesinto proteins synthesized in vitro. See the following publications andreferences cited within: Brunner, J. New Photolabeling and crosslinkingmethods, Annu. Rev Biochem, 62:483-514 (1993); and, Krieg, U. C.,Walter, P., Hohnson, A. E. Photocrosslinking of the signal sequence ofnascent preprolactin of the 54-kilodalton polypeptide of the signalrecognition particle, Proc. Natl. Acad. Sci, 83(22):8604-8608 (1986).

Previously, it has been shown that unnatural amino acids can besite-specifically incorporated into proteins in vitro by the addition ofchemically aminoacylated suppressor tRNAs to protein synthesis reactionsprogrammed with a gene containing a desired amber nonsense mutation.Using these approaches, one can substitute a number of the common twentyamino acids with close structural homologues, e.g., fluorophenylalaninefor phenylalanine, using strains auxotropic for a particular amino acid.See, e.g., Noren, C. J., Anthony-Cahill, Griffith, M. C., Schultz, P. G.A general method for site-specific incorporation of unnatural aminoacids into proteins, Science, 244: 182-188 (1989); M. W. Nowak, et al.,Science 268:439-42 (1995); Bain, J. D., Glabe, C. G., Dix, T. A.,Chamberlin, A. R., Diala, E. S. Biosynthetic site-specific Incorporationof a non-natural amino acid into a polypeptide, J. Am Chem Soc,111:8013-8014 (1989); N. Budisa et al., FASEB J. 13:41-51 (1999);Ellman, J. A., Mendel, D., Anthony-Cahill, S., Noren, C. J., Schultz, P.G. Biosynthetic method for introducing unnatural amino acidssite-specifically into proteins, Methods in Enz., 301-336 (1992); and,Mendel, D., Cornish, V. W. & Schultz, P. G. Site-Directed Mutagenesiswith an Expanded Genetic Code, Annu Rev Biophys. Biomol Struct. 24,435-62 (1995).

For example, a suppressor tRNA was prepared that recognized the stopcodon UAG and was chemically aminoacylated with an unnatural amino acid.Conventional site-directed mutagenesis was used to introduce the stopcodon TAG, at the site of interest in the protein gene. See, e.g.,Sayers, J. R., Schmidt, W. Eckstein, F. 5′, 3′ Exonuclease inphosphorothioate-based olignoucleotide-directed mutagensis, NucleicAcids Res, 16(3):791-802 (1988). When the acylated suppressor tRNA andthe mutant gene were combined in an in vitro transcription/translationsystem, the unnatural amino acid was incorporated in response to the UAGcodon which gave a protein containing that amino acid at the specifiedposition. Experiments using [³H]-Phe and experiments with α-hydroxyacids demonstrated that only the desired amino acid is incorporated atthe position specified by the UAG codon and that this amino acid is notincorporated at any other site in the protein. See, e.g., Noren, et al,supra; Kobayashi et al., (2003) Nature Structural Biology 10(6):425-432;and, Ellman, J. A., Mendel, D., Schultz, P. G. Site-specificincorporation of novel backbone structures into proteins, Science,255(5041):197-200 (1992).

Microinjection techniques have also been use incorporate unnatural aminoacids into proteins. See, e.g., M. W. Nowak, P. C. Kearney, J. R.Sampson, M. E. Saks, C. G. Labarca, S. K. Silverman, W. G. Zhong, J.Thorson, J. N. Abelson, N. Davidson, P. G. Schultz, D. A. Dougherty andH. A. Lester, Science, 268:439 (1995); and, D. A. Dougherty, Curr. Opin.Chem. Biol., 4:645 (2000). A Xenopus oocyte was coinjected with two RNAspecies made in vitro: an mRNA encoding the target protein with a UAGstop codon at the amino acid position of interest and an ambersuppressor tRNA aminoacylated with the desired unnatural amino acid. Thetranslational machinery of the oocyte then inserts the unnatural aminoacid at the position specified by UAG. This method has allowed in vivostructure-function studies of integral membrane proteins, which aregenerally not amenable to in vitro expression systems. Examples includethe incorporation of a fluorescent amino acid into tachykininneurokinin-2 receptor to measure distances by fluorescence resonanceenergy transfer, see, e.g., G. Turcatti, K. Nemeth, M. D. Edgerton, U.Meseth, F. Talabot, M. Peitsch, J. Knowles, H. Vogel and A. Chollet, J.Biol. Chem., 271:19991 (1996); the incorporation of biotinylated aminoacids to identify surface-exposed residues in ion channels, see, e.g.,J. P. Gallivan, H. A. Lester and D. A. Dougherty, Chem. Biol., 4:739(1997); the use of caged tyrosine analogs to monitor conformationalchanges in an ion channel in real time, see, e.g., J. C. Miller, S. K.Silverman, P. M. England, D. A. Dougherty and H. A. Lester, Neuron,20:619 (1998); and, the use of alpha hydroxy amino acids to change ionchannel backbones for probing their gating mechanisms. See, e.g., P. M.England, Y. Zhang, D. A. Dougherty and H. A. Lester, Cell, 96:89 (1999);and, T. Lu, A. Y. Ting, J. Mainland, L. Y. Jan, P. G. Schultz and J.Yang, Nat. Neurosci., 4:239 (2001).

The ability to incorporate unnatural amino acids directly into proteinsin vivo offers the advantages of high yields of mutant proteins,technical ease, the potential to study the mutant proteins in cells orpossibly in living organisms and the use of these mutant proteins intherapeutic treatments. The ability to include unnatural amino acidswith various sizes, acidities, nucleophilicities, hydrophobicities, andother properties into proteins can greatly expand our ability torationally and systematically manipulate the structures of proteins,both to probe protein function and create new proteins or organisms withnovel properties. However, the process is difficult, because the complexnature of tRNA-synthetase interactions that are required to achieve ahigh degree of fidelity in protein translation.

In one attempt to site-specifically incorporate para-F-Phe, a yeastamber suppressor tRNAPheCUA/phenylalanyl-tRNA synthetase pair was usedin a p-F-Phe resistant, Phe auxotrophic Escherichia coli strain. See,e.g., R. Furter, Protein Sci., 7:419 (1998).

It may also be possible to obtain expression of a hGH polynucleotide ofthe present invention using a cell-free (in-vitro) translational system.In these systems, which can include either mRNA as a template (in-vitrotranslation) or DNA as a template (combined in-vitro transcription andtranslation), the in vitro synthesis is directed by the ribosomes.Considerable effort has been applied to the development of cell-freeprotein expression systems. See, e.g., Kim, D.-M. and J. R. Swartz,Biotechnology and Bioengineering, 74:309-316 (2001); Kim, D.-M. and J.R. Swartz, Biotechnology Letters, 22, 1537-1542, (2000); Kim, D.-M., andJ. R. Swartz, Biotechnology Progress, 16, 385-390, (2000); Kim, D.-M.,and J. R. Swartz, Biotechnology and Bioengineering, 66, 180-188, (1999);and Patnaik, R. and J. R. Swartz, Biotechniques 24, 862-868, (1998);U.S. Pat. No. 6,337,191; U.S. Patent Publication No. 2002/0081660; WO00/55353; WO 90/05785, which are incorporated by reference herein.Another approach that may be applied to the expression of hGHpolypeptides comprising a non-naturally encoded amino acid includes themRNA-peptide fusion technique. See, e.g., R. Roberts and J. Szostak,Proc. Natl. Acad. Sci. (USA) 94:12297-12302 (1997); A. Frankel, et al.,Chemistry & Biology 10:1043-1050 (2003). In this approach, an mRNAtemplate linked to puromycin is translated into peptide on the ribosome.If one or more tRNA molecules has been modified, non-natural amino acidscan be incorporated into the peptide as well. After the last mRNA codonhas been read, puromycin captures the C-terminus of the peptide. If theresulting mRNA-peptide conjugate is found to have interesting propertiesin an in vitro assay, its identity can be easily revealed from the mRNAsequence. In this way, one may screen libraries of hGH polypeptidescomprising one or more non-naturally encoded amino acids to identifypolypeptides having desired properties. More recently, in vitro ribosometranslations with purified components have been reported that permit thesynthesis of peptides substituted with non-naturally encoded aminoacids. See, e.g., A. Forster et al., Proc. Natl. Acad. Sci. (USA)100:6353 (2003).

IX. Macromolecular Polymers Coupled to hGH Polypeptides

Various modifications to the non-natural amino acid polypeptidesdescribed herein can be effected using the compositions, methods,techniques and strategies described herein. These modifications includethe incorporation of further functionality onto the non-natural aminoacid component of the polypeptide, including but not limited to, alabel; a dye; a polymer; a water-soluble polymer; a derivative ofpolyethylene glycol; a photocrosslinker; a cytotoxic compound; a drug;an affinity label; a photoaffinity label; a reactive compound; a resin;a second protein or polypeptide or polypeptide analog; an antibody orantibody fragment; a metal chelator; a cofactor; a fatty acid; acarbohydrate; a polynucleotide; a DNA; a RNA; an antisensepolynucleotide; an inhibitory ribonucleic acid; a biomaterial; ananoparticle; a spin label; a fluorophore, a metal-containing moiety; aradioactive moiety; a novel functional group; a group that covalently ornoncovalently interacts with other molecules; a photocaged moiety; aphotoisomerizable moiety; biotin; a derivative of biotin; a biotinanalogue; a moiety incorporating a heavy atom; a chemically cleavablegroup; a photocleavable group; an elongated side chain; a carbon-linkedsugar; a redox-active agent; an amino thioacid; a toxic moiety; anisotopically labeled moiety; a biophysical probe; a phosphorescentgroup; a chemiluminescent group; an electron dense group; a magneticgroup; an intercalating group; a chromophore; an energy transfer agent;a biologically active agent; a detectable label; a small molecule; orany combination of the above, or any other desirable compound orsubstance. As an illustrative, non-limiting example of the compositions,methods, techniques and strategies described herein, the followingdescription will focus on adding macromolecular polymers to thenon-natural amino acid polypeptide with the understanding that thecompositions, methods, techniques and strategies described thereto arealso applicable (with appropriate modifications, if necessary and forwhich one of skill in the art could make with the disclosures herein) toadding other functionalities, including but not limited to those listedabove.

A wide variety of macromolecular polymers and other molecules can belinked to hGH polypeptides of the present invention to modulatebiological properties of the hGH polypeptide, and/or provide newbiological properties to the hGH molecule. These macromolecular polymerscan be linked to the hGH polypeptide via a naturally encoded amino acid,via a non-naturally encoded amino acid, or any functional substituent ofa natural or non-natural amino acid, or any substituent or functionalgroup added to a natural or non-natural amino acid.

The present invention provides substantially homogenous preparations ofpolymer:protein conjugates. “Substantially homogenous” as used hereinmeans that polymer:protein conjugate molecules are observed to begreater than half of the total protein. The polymer:protein conjugatehas biological activity and the present “substantially homogenous”PEGylated hGH polypeptide preparations provided herein are those whichare homogenous enough to display the advantages of a homogenouspreparation, e.g., ease in clinical application in predictability of lotto lot pharmacokinetics.

One may also choose to prepare a mixture of polymer:protein conjugatemolecules, and the advantage provided herein is that one may select theproportion of mono-polymer:protein conjugate to include in the mixture.Thus, if desired, one may prepare a mixture of various proteins withvarious numbers of polymer moieties attached (i.e., di-, tri-, tetra-,etc.) and combine said conjugates with the mono-polymer:proteinconjugate prepared using the methods of the present invention, and havea mixture with a predetermined proportion of mono-polymer:proteinconjugates.

The polymer selected may be water soluble so that the protein to whichit is attached does not precipitate in an aqueous environment, such as aphysiological environment. The polymer may be branched or unbranched.Preferably, for therapeutic use of the end-product preparation, thepolymer will be pharmaceutically acceptable.

The proportion of polyethylene glycol molecules to protein moleculeswill vary, as will their concentrations in the reaction mixture. Ingeneral, the optimum ratio (in terms of efficiency of reaction in thatthere is minimal excess unreacted protein or polymer) may be determinedby the molecular weight of the polyethylene glycol selected and on thenumber of available reactive groups available. As relates to molecularweight, typically the higher the molecular weight of the polymer, thefewer number of polymer molecules which may be attached to the protein.Similarly, branching of the polymer should be taken into account whenoptimizing these parameters. Generally, the higher the molecular weight(or the more branches) the higher the polymer:protein ratio.

As used herein, and when contemplating PEG:hGH polypeptide conjugates,the term “therapeutically effective amount” refers to an amount whichgives an increase in hematocrit that provides benefit to a patient. Theamount will vary from one individual to another and will depend upon anumber of factors, including the overall physical condition of thepatient and the underlying cause of anemia. For example, atherapeutically effective amount of hGH polypeptide for a patientsuffering from chronic renal failure is 50 to 150 units/kg three timesper week. The amount of hGH polypeptide used for therapy gives anacceptable rate of hematocrit increase and maintains the hematocrit at abeneficial level (usually at least about 30% and typically in a range of30% to 36%). A therapeutically effective amount of the presentcompositions may be readily ascertained by one skilled in the art usingpublicly available materials and procedures.

The water soluble polymer may be any structural form including but notlimited to linear, forked or branched. Typically, the water solublepolymer is a poly(alkylene glycol), such as poly(ethylene glycol) (PEG),but other water soluble polymers can also be employed. By way ofexample, PEG is used to describe certain embodiments of this invention.

PEG is a well-known, water soluble polymer that is commerciallyavailable or can be prepared by ring-opening polymerization of ethyleneglycol according to methods well known in the art (Sandler and Karo,Polymer Synthesis, Academic Press, New York, Vol. 3, pages 138-161). Theterm “PEG” is used broadly to encompass any polyethylene glycolmolecule, without regard to size or to modification at an end of thePEG, and can be represented as linked to the hGH polypeptide by theformula:XO—(CH₂CH₂O)_(n)—CH₂CH₂—Ywhere n is 2 to 10,000 and X is H or a terminal modification, includingbut not limited to, a C₁₋₄ alkyl.

In some cases, a PEG used in the invention terminates on one end withhydroxy or methoxy, i.e., X is H or CH₃ (“methoxy PEG”). Alternatively,the PEG can terminate with a reactive group, thereby forming abifunctional polymer. Typical reactive groups can include those reactivegroups that are commonly used to react with the functional groups foundin the 20 common amino acids (including but not limited to, maleimidegroups, activated carbonates (including but not limited to,p-nitrophenyl ester), activated esters (including but not limited to,N-hydroxysuccinimide, p-nitrophenyl ester) and aldehydes) as well asfunctional groups that are inert to the 20 common amino acids but thatreact specifically with complementary functional groups present innon-naturally encoded amino acids (including but not limited to, azidegroups, alkyne groups). It is noted that the other end of the PEG, whichis shown in the above formula by Y, will attach either directly orindirectly to a hGH polypeptide via a naturally-occurring ornon-naturally encoded amino acid. For instance, Y may be an amide,carbamate or urea linkage to an amine group (including but not limitedto, the epsilon amine of lysine or the N-terminus) of the polypeptide.Alternatively, Y may be a maleimide linkage to a thiol group (includingbut not limited to, the thiol group of cysteine). Alternatively, Y maybe a linkage to a residue not commonly accessible via the 20 commonamino acids. For example, an azide group on the PEG can be reacted withan alkyne group on the hGH polypeptide to form a Huisgen [3+2]cycloaddition product. Alternatively, an alkyne group on the PEG can bereacted with an azide group present in a non-naturally encoded aminoacid to form a similar product. In some embodiments, a strongnucleophile (including but not limited to, hydrazine, hydrazide,hydroxylamine, semicarbazide) can be reacted with an aldehyde or ketonegroup present in a non-naturally encoded amino acid to form a hydrazone,oxime or semicarbazone, as applicable, which in some cases can befurther reduced by treatment with an appropriate reducing agent.Alternatively, the strong nucleophile can be incorporated into the hGHpolypeptide via a non-naturally encoded amino acid and used to reactpreferentially with a ketone or aldehyde group present in the watersoluble polymer.

Any molecular mass for a PEG can be used as practically desired,including but not limited to, from about 100 Daltons (Da) to 100,000 Daor more as desired (including but not limited to, sometimes 0.1-50 kDaor 10-40 kDa). Branched chain PEGs, including but not limited to, PEGmolecules with each chain having a MW ranging from 1-100 kDa (includingbut not limited to, 1-50 kDa or 5-20 kDa) can also be used. A wide rangeof PEG molecules are described in, including but not limited to, theShearwater Polymers, Inc. catalog, Nektar Therapeutics catalog,incorporated herein by reference.

Generally, at least one terminus of the PEG molecule is available forreaction with the non-naturally-encoded amino acid. For example, PEGderivatives bearing alkyne and azide moieties for reaction with aminoacid side chains can be used to attach PEG to non-naturally encodedamino acids as described herein. If the non-naturally encoded amino acidcomprises an azide, then the PEG will typically contain either an alkynemoiety to effect formation of the [3+2] cycloaddition product or anactivated PEG species (i.e., ester, carbonate) containing a phosphinegroup to effect formation of the amide linkage. Alternatively, if thenon-naturally encoded amino acid comprises an alkyne, then the PEG willtypically contain an azide moiety to effect formation of the [3+2]Huisgen cycloaddition product. If the non-naturally encoded amino acidcomprises a carbonyl group, the PEG will typically comprise a potentnucleophile (including but not limited to, a hydrazide, hydrazine,hydroxylamine, or semicarbazide functionality) in order to effectformation of corresponding hydrazone, oxime, and semicarbazone linkages,respectively. In other alternatives, a reverse of the orientation of thereactive groups described above can be used, i.e., an azide moiety inthe non-naturally encoded amino acid can be reacted with a PEGderivative containing an alkyne.

In some embodiments, the hGH polypeptide variant with a PEG derivativecontains a chemical functionality that is reactive with the chemicalfunctionality present on the side chain of the non-naturally encodedamino acid.

The invention provides in some embodiments azide- andacetylene-containing polymer derivatives comprising a water solublepolymer backbone having an average molecular weight from about 800 Da toabout 100,000 Da. The polymer backbone of the water-soluble polymer canbe poly(ethylene glycol). However, it should be understood that a widevariety of water soluble polymers including but not limited topoly(ethylene)glycol and other related polymers, including poly(dextran)and poly(propylene glycol), are also suitable for use in the practice ofthis invention and that the use of the term PEG or poly(ethylene glycol)is intended to encompass and include all such molecules. The term PEGincludes, but is not limited to, poly(ethylene glycol) in any of itsforms, including bifunctional PEG, multiarmed PEG, derivatized PEG,forked PEG, branched PEG, pendent PEG (i.e. PEG or related polymershaving one or more functional groups pendent to the polymer backbone),or PEG with degradable linkages therein.

PEG is typically clear, colorless, odorless, soluble in water, stable toheat, inert to many chemical agents, does not hydrolyze or deteriorate,and is generally non-toxic. Poly(ethylene glycol) is considered to bebiocompatible, which is to say that PEG is capable of coexistence withliving tissues or organisms without causing harm. More specifically, PEGis substantially non-immunogenic, which is to say that PEG does not tendto produce an immune response in the body. When attached to a moleculehaving some desirable function in the body, such as a biologicallyactive agent, the PEG tends to mask the agent and can reduce oreliminate any immune response so that an organism can tolerate thepresence of the agent. PEG conjugates tend not to produce a substantialimmune response or cause clotting or other undesirable effects. PEGhaving the formula —CH₂CH₂O—(CH₂CH₂O)_(n)—CH₂CH₂—, where n is from about3 to about 4000, typically from about 20 to about 2000, is suitable foruse in the present invention. PEG having a molecular weight of fromabout 800 Da to about 100,000 Da are in some embodiments of the presentinvention particularly useful as the polymer backbone.

The polymer backbone can be linear or branched. Branched polymerbackbones are generally known in the art. Typically, a branched polymerhas a central branch core moiety and a plurality of linear polymerchains linked to the central branch core. PEG is commonly used inbranched forms that can be prepared by addition of ethylene oxide tovarious polyols, such as glycerol, glycerol oligomers, pentaerythritoland sorbitol. The central branch moiety can also be derived from severalamino acids, such as lysine. The branched poly(ethylene glycol) can berepresented in general form as R(-PEG-OH)_(m) in which R is derived froma core moiety, such as glycerol, glycerol oligomers, or pentaerythritol,and m represents the number of arms. Multi-armed PEG molecules, such asthose described in U.S. Pat. Nos. 5,932,462 5,643,575; 5,229,490;4,289,872; U.S. Pat. Appl. 2003/0143596; WO 96/21469; and WO 93/21259,each of which is incorporated by reference herein in its entirety, canalso be used as the polymer backbone.

Branched PEG can also be in the form of a forked PEG represented byPEG(-YCHZ₂)_(n), where Y is a linking group and Z is an activatedterminal group linked to CH by a chain of atoms of defined length.

Yet another branched form, the pendant PEG, has reactive groups, such ascarboxyl, along the PEG backbone rather than at the end of PEG chains.

In addition to these forms of PEG, the polymer can also be prepared withweak or degradable linkages in the backbone. For example, PEG can beprepared with ester linkages in the polymer backbone that are subject tohydrolysis. As shown below, this hydrolysis results in cleavage of thepolymer into fragments of lower molecular weight:-PEG-CO₂-PEG-+H₂O→PEG-CO₂H+HO-PEG-It is understood by those skilled in the art that the term poly(ethyleneglycol) or PEG represents or includes all the forms known in the artincluding but not limited to those disclosed herein.

Many other polymers are also suitable for use in the present invention.In some embodiments, polymer backbones that are water-soluble, with from2 to about 300 termini, are particularly useful in the invention.Examples of suitable polymers include, but are not limited to, otherpoly(alkylene glycols), such as poly(propylene glycol) (“PPG”),copolymers thereof (including but not limited to copolymers of ethyleneglycol and propylene glycol), terpolymers thereof, mixtures thereof, andthe like. Although the molecular weight of each chain of the polymerbackbone can vary, it is typically in the range of from about 800 Da toabout 100,000 Da, often from about 6,000 Da to about 80,000 Da.

Those of ordinary skill in the art will recognize that the foregoinglist for substantially water soluble backbones is by no means exhaustiveand is merely illustrative, and that all polymeric materials having thequalities described above are contemplated as being suitable for use inthe present invention.

In some embodiments of the present invention the polymer derivatives are“multi-functional”, meaning that the polymer backbone has at least twotermini, and possibly as many as about 300 termini, functionalized oractivated with a functional group. Multifunctional polymer derivativesinclude, but are not limited to, linear polymers having two termini,each terminus being bonded to a functional group which may be the sameor different.

In one embodiment, the polymer derivative has the structure:X-A-POLY-B—N═N═Nwherein:N═N═N is an azide moiety;B is a linking moiety, which may be present or absent;POLY is a water-soluble non-antigenic polymer;A is a linking moiety, which may be present or absent and which may bethe same as B or different; andX is a second functional group.Examples of a linking moiety for A and B include, but are not limitedto, a multiply-functionalized alkyl group containing up to 18, and morepreferably between 1-10 carbon atoms. A heteroatom such as nitrogen,oxygen or sulfur may be included with the alkyl chain. The alkyl chainmay also be branched at a heteroatom. Other examples of a linking moietyfor A and B include, but are not limited to, a multiply functionalizedaryl group, containing up to 10 and more preferably 5-6 carbon atoms.The aryl group may be substituted with one more carbon atoms, nitrogen,oxygen or sulfur atoms. Other examples of suitable linking groupsinclude those linking groups described in U.S. Pat. Nos. 5,932,462;5,643,575; and U.S. Pat. Appl. Publication 2003/0143596, each of whichis incorporated by reference herein. Those of ordinary skill in the artwill recognize that the foregoing list for linking moieties is by nomeans exhaustive and is merely illustrative, and that all linkingmoieties having the qualities described above are contemplated to besuitable for use in the present invention.

Examples of suitable functional groups for use as X include, but are notlimited to, hydroxyl, protected hydroxyl, alkoxyl, active ester, such asN-hydroxysuccinimidyl esters and 1-benzotriazolyl esters, activecarbonate, such as N-hydroxysuccinimidyl carbonates and 1-benzotriazolylcarbonates, acetal, aldehyde, aldehyde hydrates, alkenyl, acrylate,methacrylate, acrylamide, active sulfone, amine, aminooxy, protectedamine, hydrazide, protected hydrazide, protected thiol, carboxylic acid,protected carboxylic acid, isocyanate, isothiocyanate, maleimide,vinylsulfone, dithiopyridine, vinylpyridine, iodoacetamide, epoxide,glyoxals, diones, mesylates, tosylates, tresylate, alkene, ketone, andazide. As is understood by those skilled in the art, the selected Xmoiety should be compatible with the azide group so that reaction withthe azide group does not occur. The azide-containing polymer derivativesmay be homobifunctional, meaning that the second functional group (i.e.,X) is also an azide moiety, or heterobifunctional, meaning that thesecond functional group is a different functional group.

The term “protected” refers to the presence of a protecting group ormoiety that prevents reaction of the chemically reactive functionalgroup under certain reaction conditions. The protecting group will varydepending on the type of chemically reactive group being protected. Forexample, if the chemically reactive group is an amine or a hydrazide,the protecting group can be selected from the group oftert-butyloxycarbonyl (t-Boc) and 9-fluorenylmethoxycarbonyl (Fmoc). Ifthe chemically reactive group is a thiol, the protecting group can beorthopyridyldisulfide. If the chemically reactive group is a carboxylicacid, such as butanoic or propionic acid, or a hydroxyl group, theprotecting group can be benzyl or an alkyl group such as methyl, ethyl,or tert-butyl. Other protecting groups known in the art may also be usedin the present invention.

Specific examples of terminal functional groups in the literatureinclude, but are not limited to, N-succinimidyl carbonate (see e.g.,U.S. Pat. Nos. 5,281,698, 5,468,478), amine (see, e.g., Buckmann et al.Makromol. Chem. 182:1379 (1981), Zaplipsky et al. Eur. Polym. J. 19:1177(1983)), hydrazide (See, e.g., Andresz et al. Makromol. Chem. 179:301(1978)), succinimidyl propionate and succinimidyl butanoate (see, e.g.,Olson et al. in Poly(ethylene glycol) Chemistry & BiologicalApplications, pp 170-181, Harris & Zaplipsky Eds., ACS, Washington,D.C., 1997; see also U.S. Pat. No. 5,672,662), succinimidyl succinate(See, e.g., Abuchowski et al. Cancer Biochem. Biophys. 7:175 (1984) andJoppich et al. Macrolol. Chem. 180:1381 (1979), succinimidyl ester (see,e.g., U.S. Pat. No. 4,670,417), benzotriazole carbonate (see, e.g., U.S.Pat. No. 5,650,234), glycidyl ether (see, e.g., Pitha et al. Eur. J.Biochem. 94:11 (1979), Elling et al., Biotech. Appl. Biochem. 13:354(1991), oxycarbonylimidazole (see, e.g., Beauchamp, et al., Anal.Biochem. 131:25 (1983), Tondelli et al. J. Controlled Release 1:251(1985)), p-nitrophenyl carbonate (see, e.g., Veronese, et al., Appl.Biochem. Biotech., 11: 141 (1985); and Sartore et al., Appl. Biochem.Biotech., 27:45 (1991)), aldehyde (see, e.g., Harris et al. J. Polym.Sci. Chem. Ed. 22:341 (1984), U.S. Pat. No. 5,824,784, U.S. Pat. No.5,252,714), maleimide (see, e.g., Goodson et al. Bio/Technology 8:343(1990), Romani et al. in Chemistry of Peptides and Proteins 2:29(1984)), and Kogan, Synthetic Comm. 22:2417 (1992)),orthopyridyl-disulfide (see, e.g., Woghiren, et al. Bioconj. Chem. 4:314(1993)), acrylol (see, e.g., Sawhney et al., Macromolecules, 26:581(1993)), vinylsulfone (see, e.g., U.S. Pat. No. 5,900,461). All of theabove references and patents are incorporated herein by reference.

In certain embodiments of the present invention, the polymer derivativesof the invention comprise a polymer backbone having the structure:X—CH₂CH₂O—(CH₂CH₂O)_(n)—CH₂CH₂—N═N═Nwherein:X is a functional group as described above; andn is about 20 to about 4000.In another embodiment, the polymer derivatives of the invention comprisea polymer backbone having the structure:X—CH₂CH₂O—(CH₂CH₂O)_(n)—CH₂CH₂—O—(CH₂)_(m)—W—N═N═Nwherein:W is an aliphatic or aromatic linker moiety comprising between 1-10carbon atoms;n is about 20 to about 4000; andX is a functional group as described above. m is between 1 and 10.

The azide-containing PEG derivatives of the invention can be prepared bya variety of methods known in the art and/or disclosed herein. In onemethod, shown below, a water soluble polymer backbone having an averagemolecular weight from about 800 Da to about 100,000 Da, the polymerbackbone having a first terminus bonded to a first functional group anda second terminus bonded to a suitable leaving group, is reacted with anazide anion (which may be paired with any of a number of suitablecounter-ions, including sodium, potassium, tert-butylammonium and soforth). The leaving group undergoes a nucleophilic displacement and isreplaced by the azide moiety, affording the desired azide-containing PEGpolymer.X-PEG-L+N₃ ⁻→X-PEG-N₃

As shown, a suitable polymer backbone for use in the present inventionhas the formula X-PEG-L, wherein PEG is poly(ethylene glycol) and X is afunctional group which does not react with azide groups and L is asuitable leaving group. Examples of suitable functional groups include,but are not limited to, hydroxyl, protected hydroxyl, acetal, alkenyl,amine, aminooxy, protected amine, protected hydrazide, protected thiol,carboxylic acid, protected carboxylic acid, maleimide, dithiopyridine,and vinylpyridine, and ketone. Examples of suitable leaving groupsinclude, but are not limited to, chloride, bromide, iodide, mesylate,tresylate, and tosylate.

In another method for preparation of the azide-containing polymerderivatives of the present invention, a linking agent bearing an azidefunctionality is contacted with a water soluble polymer backbone havingan average molecular weight from about 800 Da to about 100,000 Da,wherein the linking agent bears a chemical functionality that will reactselectively with a chemical functionality on the PEG polymer, to form anazide-containing polymer derivative product wherein the azide isseparated from the polymer backbone by a linking group.

An exemplary reaction scheme is shown below:X-PEG-M+N-linker-N═N═N→PG-X-PEG-linker-N═N═Nwherein:PEG is poly(ethylene glycol) and X is a capping group such as alkoxy ora functional group as described above; andM is a functional group that is not reactive with the azidefunctionality but that will react efficiently and selectively with the Nfunctional group.

Examples of suitable functional groups include, but are not limited to,M being a carboxylic acid, carbonate or active ester if N is an amine; Mbeing a ketone if N is a hydrazide or aminooxy moiety; M being a leavinggroup if N is a nucleophile.

Purification of the crude product may be accomplished by known methodsincluding, but are not limited to, precipitation of the product followedby chromatography, if necessary.

A more specific example is shown below in the case of PEG diamine, inwhich one of the amines is protected by a protecting group moiety suchas tert-butyl-Boc and the resulting mono-protected PEG diamine isreacted with a linking moiety that bears the azide functionality:BocHN-PEG-NH₂+HO₂C—(CH₂)₃—N═N═N

In this instance, the amine group can be coupled to the carboxylic acidgroup using a variety of activating agents such as thionyl chloride orcarbodiimide reagents and N-hydroxysuccinimide or N-hydroxybenzotriazoleto create an amide bond between the monoamine PEG derivative and theazide-bearing linker moiety. After successful formation of the amidebond, the resulting N-tert-butyl-Boc-protected azide-containingderivative can be used directly to modify bioactive molecules or it canbe further elaborated to install other useful functional groups. Forinstance, the N-t-Boc group can be hydrolyzed by treatment with strongacid to generate an omega-amino-PEG-azide. The resulting amine can beused as a synthetic handle to install other useful functionality such asmaleimide groups, activated disulfides, activated esters and so forthfor the creation of valuable heterobifunctional reagents.

Heterobifunctional derivatives are particularly useful when it isdesired to attach different molecules to each terminus of the polymer.For example, the omega-N-amino-N-azido PEG would allow the attachment ofa molecule having an activated electrophilic group, such as an aldehyde,ketone, activated ester, activated carbonate and so forth, to oneterminus of the PEG and a molecule having an acetylene group to theother terminus of the PEG.

In another embodiment of the invention, the polymer derivative has thestructure:X-A-POLY-B-C≡C—Rwherein:R can be either H or an alkyl, alkene, alkyoxy, or aryl or substitutedaryl group;B is a linking moiety, which may be present or absent;POLY is a water-soluble non-antigenic polymer;A is a linking moiety, which may be present or absent and which may bethe same as B or different; andX is a second functional group.

Examples of a linking moiety for A and B include, but are not limitedto, a multiply-functionalized alkyl group containing up to 18, and morepreferably between 1-10 carbon atoms. A heteroatom such as nitrogen,oxygen or sulfur may be included with the alkyl chain. The alkyl chainmay also be branched at a heteroatom. Other examples of a linking moietyfor A and B include, but are not limited to, a multiply functionalizedaryl group, containing up to 10 and more preferably 5-6 carbon atoms.The aryl group may be substituted with one more carbon atoms, nitrogen,oxygen, or sulfur atoms. Other examples of suitable linking groupsinclude those linking groups described in U.S. Pat. Nos. 5,932,462 and5,643,575 and U.S. Pat. Appl. Publication 2003/0143596, each of which isincorporated by reference herein. Those of ordinary skill in the artwill recognize that the foregoing list for linking moieties is by nomeans exhaustive and is intended to be merely illustrative, and that awide variety of linking moieties having the qualities described aboveare contemplated to be useful in the present invention.

Examples of suitable functional groups for use as X include hydroxyl,protected hydroxyl, alkoxyl, active ester, such as N-hydroxysuccinimidylesters and 1-benzotriazolyl esters, active carbonate, such asN-hydroxysuccinimidyl carbonates and 1-benzotriazolyl carbonates,acetal, aldehyde, aldehyde hydrates, alkenyl, acrylate, methacrylate,acrylamide, active sulfone, amine, aminooxy, protected amine, hydrazide,protected hydrazide, protected thiol, carboxylic acid, protectedcarboxylic acid, isocyanate, isothiocyanate, maleimide, vinylsulfone,dithiopyridine, vinylpyridine, iodoacetamide, epoxide, glyoxals, diones,mesylates, tosylates, and tresylate, alkene, ketone, and acetylene. Aswould be understood, the selected X moiety should be compatible with theacetylene group so that reaction with the acetylene group does notoccur. The acetylene-containing polymer derivatives may behomobifunctional, meaning that the second functional group (i.e., X) isalso an acetylene moiety, or heterobifunctional, meaning that the secondfunctional group is a different functional group.

In another embodiment of the present invention, the polymer derivativescomprise a polymer backbone having the structure:X—CH₂CH₂O—(CH₂CH₂O)_(n)—CH₂CH₂—O—(CH₂)_(m)—C≡CHwherein:X is a functional group as described above;n is about 20 to about 4000; andm is between 1 and 10.Specific examples of each of the heterobifunctional PEG polymers areshown below.

The acetylene-containing PEG derivatives of the invention can beprepared using methods known to those skilled in the art and/ordisclosed herein. In one method, a water soluble polymer backbone havingan average molecular weight from about 800 Da to about 100,000 Da, thepolymer backbone having a first terminus bonded to a first functionalgroup and a second terminus bonded to a suitable nucleophilic group, isreacted with a compound that bears both an acetylene functionality and aleaving group that is suitable for reaction with the nucleophilic groupon the PEG. When the PEG polymer bearing the nucleophilic moiety and themolecule bearing the leaving group are combined, the leaving groupundergoes a nucleophilic displacement and is replaced by thenucleophilic moiety, affording the desired acetylene-containing polymer.X-PEG-Nu+L-A-C→X-PEG-Nu-A-C≡CR′

As shown, a preferred polymer backbone for use in the reaction has theformula X-PEG-Nu, wherein PEG is poly(ethylene glycol), Nu is anucleophilic moiety and X is a functional group that does not react withNu, L or the acetylene functionality.

Examples of Nu include, but are not limited to, amine, alkoxy, aryloxy,sulfhydryl, imino, carboxylate, hydrazide, aminoxy groups that wouldreact primarily via a SN2-type mechanism. Additional examples of Nugroups include those functional groups that would react primarily via annucleophilic addition reaction. Examples of L groups include chloride,bromide, iodide, mesylate, tresylate, and tosylate and other groupsexpected to undergo nucleophilic displacement as well as ketones,aldehydes, thioesters, olefins, alpha-beta unsaturated carbonyl groups,carbonates and other electrophilic groups expected to undergo additionby nucleophiles.

In another embodiment of the present invention, A is an aliphatic linkerof between 1-10 carbon atoms or a substituted aryl ring of between 6-14carbon atoms. X is a functional group which does not react with azidegroups and L is a suitable leaving group

In another method for preparation of the acetylene-containing polymerderivatives of the invention, a PEG polymer having an average molecularweight from about 800 Da to about 100,000 Da, bearing either a protectedfunctional group or a capping agent at one terminus and a suitableleaving group at the other terminus is contacted by an acetylene anion.

An exemplary reaction scheme is shown below:X-PEG-L+-C≡CR′→X-PEG-C≡CR′wherein:PEG is poly(ethylene glycol) and X is a capping group such as alkoxy ora functional group as described above; andR′ is either H, an alkyl, alkoxy, aryl or aryloxy group or a substitutedalkyl, alkoxyl, aryl or aryloxy group.

In the example above, the leaving group L should be sufficientlyreactive to undergo SN2-type displacement when contacted with asufficient concentration of the acetylene anion. The reaction conditionsrequired to accomplish SN2 displacement of leaving groups by acetyleneanions are well known in the art.

Purification of the crude product can usually be accomplished by methodsknown in the art including, but are not limited to, precipitation of theproduct followed by chromatography, if necessary.

Water soluble polymers can be linked to the hGH polypeptides of theinvention. The water soluble polymers may be linked via a non-naturallyencoded amino acid incorporated in the hGH polypeptide or any functionalgroup or substituent of a non-naturally encoded or naturally encodedamino acid, or any functional group or substituent added to anon-naturally encoded or naturally encoded amino acid. Alternatively,the water soluble polymers are linked to a hGH polypeptide incorporatinga non-naturally encoded amino acid via a naturally-occurring amino acid(including but not limited to, cysteine, lysine or the amine group ofthe N-terminal residue). In some cases, the hGH polypeptides of theinvention comprise 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 non-natural aminoacids, wherein one or more non-naturally-encoded amino acid(s) arelinked to water soluble polymer(s) (including but not limited to, PEGand/or oligosaccharides). In some cases, the hGH polypeptides of theinvention further comprise 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or morenaturally-encoded amino acid(s) linked to water soluble polymers. Insome cases, the hGH polypeptides of the invention comprise one or morenon-naturally encoded amino acid(s) linked to water soluble polymers andone or more naturally-occurring amino acids linked to water solublepolymers. In some embodiments, the water soluble polymers used in thepresent invention enhance the serum half-life of the hGH polypeptiderelative to the unconjugated form.

The number of water soluble polymers linked to a hGH polypeptide (i.e.,the extent of PEGylation or glycosylation) of the present invention canbe adjusted to provide an altered (including but not limited to,increased or decreased) pharmacologic, pharmacokinetic orpharmacodynamic characteristic such as in vivo half-life. In someembodiments, the half-life of hGH is increased at least about 10, 20,30, 40, 50, 60, 70, 80, 90 percent, 2-fold, 5-fold, 10-fold, 50-fold, orat least about 100-fold over an unmodified polypeptide.

PEG Derivatives Containing a Strong Nucleophilic Group (i.e., Hydrazide,Hydrazine, Hydroxylamine or Semicarbazide)

In one embodiment of the present invention, a hGH polypeptide comprisinga carbonyl-containing non-naturally encoded amino acid is modified witha PEG derivative that contains a terminal hydrazine, hydroxylamine,hydrazide or semicarbazide moiety that is linked directly to the PEGbackbone.

In some embodiments, the hydroxylamine-terminal PEG derivative will havethe structure:RO—(CH₂CH₂O)_(n)—O—(CH₂)_(m)—O—NH₂where R is a simple alkyl (methyl, ethyl, propyl, etc.), m is 2-10 and nis 100-1,000 (i.e., average molecular weight is between 5-40 kDa).

In some embodiments, the hydrazine- or hydrazide-containing PEGderivative will have the structure:RO—(CH₂CH₂O)_(n)—O—(CH₂)_(m)—X—NH—NH₂where R is a simple alkyl (methyl, ethyl, propyl, etc.), m is 2-10 and nis 100-1,000 and X is optionally a carbonyl group (C═O) that can bepresent or absent.

In some embodiments, the semicarbazide-containing PEG derivative willhave the structure:RO—(CH₂CH₂O)_(n)—O—(CH₂)_(m)—NH—C(O)—NH—NH₂where R is a simple alkyl (methyl, ethyl, propyl, etc.), m is 2-10 and nis 100-1,000.

In another embodiment of the invention, a hGH polypeptide comprising acarbonyl-containing amino acid is modified with a PEG derivative thatcontains a terminal hydroxylamine, hydrazide, hydrazine, orsemicarbazide moiety that is linked to the PEG backbone by means of anamide linkage.

In some embodiments, the hydroxylamine-terminal PEG derivatives have thestructure:RO—(CH₂CH₂O)_(n)—O—(CH₂)₂—NH—C(O)(CH₂)_(m)—O—NH₂where R is a simple alkyl (methyl, ethyl, propyl, etc.), m is 2-10 and nis 100-1,000 (i.e., average molecular weight is between 5-40 kDa).

In some embodiments, the hydrazine- or hydrazide-containing PEGderivatives have the structure:RO—(CH₂CH₂O)_(n)—O—(CH₂)₂—NH—C(O)(CH₂)_(m)—X—NH—NH₂where R is a simple alkyl (methyl, ethyl, propyl, etc.), m is 2-10, n is100-1,000 and X is optionally a carbonyl group (C═O) that can be presentor absent.

In some embodiments, the semicarbazide-containing PEG derivatives havethe structure:RO—(CH₂CH₂O)_(n)—O—(CH₂)₂—NH—C(O)(CH₂)_(m)—NH—C(O)—NH—NH₂where R is a simple alkyl (methyl, ethyl, propyl, etc.), m is 2-10 and nis 100-1,000.

In another embodiment of the invention, a hGH polypeptide comprising acarbonyl-containing amino acid is modified with a branched PEGderivative that contains a terminal hydrazine, hydroxylamine, hydrazideor semicarbazide moiety, with each chain of the branched PEG having a MWranging from 10-40 kDa and, more preferably, from 5-20 kDa.

In another embodiment of the invention, a hGH polypeptide comprising anon-naturally encoded amino acid is modified with a PEG derivativehaving a branched structure. For instance, in some embodiments, thehydrazine- or hydrazide-terminal PEG derivative will have the followingstructure:[RO—(CH₂CH₂O)_(n)—O—(CH₂)₂—NH—C(O)]₂CH(CH₂)_(m)—X—NH—NH₂where R is a simple alkyl (methyl, ethyl, propyl, etc.), m is 2-10 and nis 100-1,000, and X is optionally a carbonyl group (C═O) that can bepresent or absent.

In some embodiments, the PEG derivatives containing a semicarbazidegroup will have the structure:[RO—(CH₂CH₂O)_(n)—O—(CH₂)₂—C(O)—NH—CH₂—CH₂]₂CH—X—(CH₂)_(m)—NH—C(O)—NH—NH₂where R is a simple alkyl (methyl, ethyl, propyl, etc.), X is optionallyNH, O, S, C(O) or not present, m is 2-10 and n is 100-1,000.

In some embodiments, the PEG derivatives containing a hydroxylaminegroup will have the structure:[RO—(CH₂CH₂O)_(n)—O—(CH₂)₂—C(O)—NH—CH₂—CH₂]₂CH—X—(CH₂)_(m)—O—NH₂where R is a simple alkyl (methyl, ethyl, propyl, etc.), X is optionallyNH, O, S, C(O) or not present, m is 2-10 and n is 100-1,000.

The degree and sites at which the water soluble polymer(s) are linked tothe hGH polypeptide can modulate the binding of the hGH polypeptide tothe hGH polypeptide receptor at Site 1. In some embodiments, thelinkages are arranged such that the hGH polypeptide binds the hGHpolypeptide receptor at Site 1 with a K_(d) of about 400 nM or lower,with a K_(d) of 150 nM or lower, and in some cases with a K_(d) of 100nM or lower, as measured by an equilibrium binding assay, such as thatdescribed in Spencer et al., J. Biol. Chem., 263:7862-7867 (1988) forhGH.

Methods and chemistry for activation of polymers as well as forconjugation of peptides are described in the literature and are known inthe art. Commonly used methods for activation of polymers include, butare not limited to, activation of functional groups with cyanogenbromide, periodate, glutaraldehyde, biepoxides, epichlorohydrin,divinylsulfone, carbodiimide, sulfonyl halides, trichlorotriazine, etc.(see, R. F. Taylor, (1991), PROTEIN IMMOBILISATION. FUNDAMENTAL ANDAPPLICATIONS, Marcel Dekker, N.Y.; S. S. Wong, (1992), CHEMISTRY OFPROTEIN CONJUGATION AND CROSSLINKING, CRC Press, Boca Raton; G. T.Hermanson et al., (1993), IMMOBILIZED AFFINITY LIGAND TECHNIQUES,Academic Press, N.Y.; Dunn, R. L., et al., Eds. POLYMERIC DRUGS AND DRUGDELIVERY SYSTEMS, ACS Symposium Series Vol. 469, American ChemicalSociety, Washington, D.C. 1991).

Several reviews and monographs on the functionalization and conjugationof PEG are available. See, for example, Harris, Macronol. Chem. Phys.C25: 325-373 (1985); Scouten, Methods in Enzymology 135: 30-65 (1987);Wong et al., Enzyme Microb. Technol. 14: 866-874 (1992); Delgado et al.,Critical Reviews in Therapeutic Drug Carrier Systems 9: 249-304 (1992);Zalipsky, Bioconjugate Chem. 6: 150-165 (1995).

Methods for activation of polymers can also be found in WO 94/17039,U.S. Pat. No. 5,324,844, WO 94/18247, WO 94/04193, U.S. Pat. No.5,219,564, U.S. Pat. No. 5,122,614, WO 90/13540, U.S. Pat. No.5,281,698, and WO 93/15189, and for conjugation between activatedpolymers and enzymes including but not limited to Coagulation FactorVIII (WO 94/15625), hemoglobin (WO 94/09027), oxygen carrying molecule(U.S. Pat. No. 4,412,989), ribonuclease and superoxide dismutase(Veronese at al., App. Biochem. Biotech. 11: 141-45 (1985)). Allreferences and patents cited are incorporated by reference herein.

PEGylation (i.e., addition of any water soluble polymer) of hGHpolypeptides containing a non-naturally encoded amino acid, such asp-azido-L-phenylalanine, is carried out by any convenient method. Forexample, hGH polypeptide is PEGylated with an alkyne-terminated mPEGderivative. Briefly, an excess of solid mPEG(5000)-O—CH₂—C≡CH is added,with stirring, to an aqueous solution of p-azido-L-Phe-containing hGHpolypeptide at room temperature. Typically, the aqueous solution isbuffered with a buffer having a pK_(a) near the pH at which the reactionis to be carried out (generally about pH 4-10). Examples of suitablebuffers for PEGylation at pH 7.5, for instance, include, but are notlimited to, HEPES, phosphate, borate, TRIS-HCl, EPPS, and TES. The pH iscontinuously monitored and adjusted if necessary. The reaction istypically allowed to continue for between about 1-48 hours.

The reaction products are subsequently subjected to hydrophobicinteraction chromatography to separate the PEGylated hGH polypeptidevariants from free mPEG(5000)-O—CH₂—C≡CH and any high-molecular weightcomplexes of the pegylated hGH polypeptide which may form when unblockedPEG is activated at both ends of the molecule, thereby crosslinking hGHpolypeptide variant molecules. The conditions during hydrophobicinteraction chromatography are such that free mPEG(5000)-O—CH₂—C≡CHflows through the column, while any crosslinked PEGylated hGHpolypeptide variant complexes elute after the desired forms, whichcontain one hGH polypeptide variant molecule conjugated to one or morePEG groups. Suitable conditions vary depending on the relative sizes ofthe cross-linked complexes versus the desired conjugates and are readilydetermined by those skilled in the art. The eluent containing thedesired conjugates is concentrated by ultrafiltration and desalted bydiafiltration.

If necessary, the PEGylated hGH polypeptide obtained from thehydrophobic chromatography can be purified further by one or moreprocedures known to those skilled in the art including, but are notlimited to, affinity chromatography; anion- or cation-exchangechromatography (using, including but not limited to, DEAE SEPHAROSE);chromatography on silica; reverse phase HPLC; gel filtration (using,including but not limited to, SEPHADEX G-75); hydrophobic interactionchromatography; size-exclusion chromatography, metal-chelatechromatography; ultrafiltration/diafiltration; ethanol precipitation;ammonium sulfate precipitation; chromatofocusing; displacementchromatography; electrophoretic procedures (including but not limited topreparative isoelectric focusing), differential solubility (includingbut not limited to ammonium sulfate precipitation), or extraction.Apparent molecular weight may be estimated by GPC by comparison toglobular protein standards (PROTEIN PURIFICATION METHODS, A PRACTICALAPPROACH (Harris & Angal, Eds.) IRL Press 1989, 293-306). The purity ofthe hGH-PEG conjugate can be assessed by proteolytic degradation(including but not limited to, trypsin cleavage) followed by massspectrometry analysis. Pepinsky B., et al., J. Pharmcol. & Exp. Ther.297(3): 1059-66 (2001).

A water soluble polymer linked to an amino acid of a hGH polypeptide ofthe invention can be further derivatized or substituted withoutlimitation.

Azide-Containing PEG Derivatives

In another embodiment of the invention, a hGH polypeptide is modifiedwith a PEG derivative that contains an azide moiety that will react withan alkyne moiety present on the side chain of the non-naturally encodedamino acid. In general, the PEG derivatives will have an averagemolecular weight ranging from 1-100 kDa and, in some embodiments, from10-40 kDa.

In some embodiments, the azide-terminal PEG derivative will have thestructure:RO—(CH₂CH₂O)_(n)—O—(CH₂)_(m)—N₃where R is a simple alkyl (methyl, ethyl, propyl, etc.), m is 2-10 and nis 100-1,000 (i.e., average molecular weight is between 540 kDa).

In another embodiment, the azide-terminal PEG derivative will have thestructure:RO—(CH₂CH₂O)_(n)—O—(CH₂)_(m)—NH—C(O)—(CH₂)_(p)—N₃where R is a simple alkyl (methyl, ethyl, propyl, etc.), m is 2-10, p is2-10 and n is 100-1,000 (i.e., average molecular weight is between 540kDa).

In another embodiment of the invention, a hGH polypeptide comprising aalkyne-containing amino acid is modified with a branched PEG derivativethat contains a terminal azide moiety, with each chain of the branchedPEG having a MW ranging from 1040 kDa and, more preferably, from 5-20kDa. For instance, in some embodiments, the azide-terminal PEGderivative will have the following structure:[RO—(CH₂CH₂O)_(n)—O—(CH₂)₂—NH—C(O)]₂CH(CH₂)_(m)—X—(CH₂)_(p)N₃where R is a simple alkyl (methyl, ethyl, propyl, etc.), m is 2-10, p is2-10, and n is 100-1,000, and X is optionally an O, N, S or carbonylgroup (C═O), in each case that can be present or absent.Alkyne-Containing PEG Derivatives

In another embodiment of the invention, a hGH polypeptide is modifiedwith a PEG derivative that contains an alkyne moiety that will reactwith an azide moiety present on the side chain of the non-naturallyencoded amino acid.

In some embodiments, the alkyne-terminal PEG derivative will have thefollowing structure:RO—(CH₂CH₂O)_(n)—O—(CH₂)_(m)—C≡CHwhere R is a simple alkyl (methyl, ethyl, propyl, etc.), m is 2-10 and nis 100-1,000 (i.e., average molecular weight is between 5-40 kDa).

In another embodiment of the invention, a hGH polypeptide comprising analkyne-containing non-naturally encoded amino acid is modified with aPEG derivative that contains a terminal azide or terminal alkyne moietythat is linked to the PEG backbone by means of an amide linkage.

In some embodiments, the alkyne-terminal PEG derivative will have thefollowing structure:RO—(CH₂CH₂O)_(n)—O—(CH₂)_(m)—NH—C(O)—(CH₂)_(p)—C≡CHwhere R is a simple alkyl (methyl, ethyl, propyl, etc.), m is 2-10, p is2-10 and n is 100-1,000.

In another embodiment of the invention, a hGH polypeptide comprising anazide-containing amino acid is modified with a branched PEG derivativethat contains a terminal alkyne moiety, with each chain of the branchedPEG having a MW ranging from 10-40 kDa and, more preferably, from 5-20kDa. For instance, in some embodiments, the alkyne-terminal PEGderivative will have the following structure:[RO—(CH₂CH₂O)_(n)—O—(CH₂)₂—NH—C(O)]₂CH(CH₂)_(m)—X—(CH₂)_(p)C≡CHwhere R is a simple alkyl (methyl, ethyl, propyl, etc.), m is 2-10, p is2-10, and n is 100-1,000, and X is optionally an O, N, S or carbonylgroup (C═O), or not present.Phosphine-Containing PEG Derivatives

In another embodiment of the invention, a hGH polypeptide is modifiedwith a PEG derivative that contains an activated functional group(including but not limited to, ester, carbonate) further comprising anaryl phosphine group that will react with an azide moiety present on theside chain of the non-naturally encoded amino acid. In general, the PEGderivatives will have an average molecular weight ranging from 1-100 kDaand, in some embodiments, from 10-40 kDa.

In some embodiments, the PEG derivative will have the structure:

wherein n is 1-10; X can be O, N, S or not present, Ph is phenyl, and Wis a water soluble polymer.

In some embodiments, the PEG derivative will have the structure:

wherein X can be O, N, S or not present, Ph is phenyl, W is a watersoluble polymer and R can be H, alkyl, aryl, substituted alkyl andsubstituted aryl groups. Exemplary R groups include but are not limitedto —CH₂, —C(CH₃)₃, —OR′, —NR′R″, —SR′, -halogen, —C(O)R′, —CONR′R″,—S(O)₂R′, —S(O)₂NR′R″, —CN and —NO₂. R′, R″, R′″ and R″″ eachindependently refer to hydrogen, substituted or unsubstitutedheteroalkyl, substituted or unsubstituted aryl, including but notlimited to, aryl substituted with 1-3 halogens, substituted orunsubstituted alkyl, alkoxy or thioalkoxy groups, or arylalkyl groups.When a compound of the invention includes more than one R group, forexample, each of the R groups is independently selected as are each R′,R″, R′″ and R″″ groups when more than one of these groups is present.When R′ and R″ are attached to the same nitrogen atom, they can becombined with the nitrogen atom to form a 5-, 6-, or 7-membered ring.For example, —NR′R″ is meant to include, but not be limited to,1-pyrrolidinyl and 4-morpholinyl. From the above discussion ofsubstituents, one of skill in the art will understand that the term“alkyl” is meant to include groups including carbon atoms bound togroups other than hydrogen groups, such as haloalkyl (including but notlimited to, —CF₃ and —CH₂CF₃) and acyl (including but not limited to,—C(O)CH₃, —C(O)CF₃, —C(O)CH₂OCH₃, and the like).Other PEG Derivatives and General PEGylation Techniques

Other exemplary PEG molecules that may be linked to hGH polypeptides, aswell as PEGylation methods include those described in, e.g., U.S. PatentPublication No. 2004/0001838; 2002/0052009; 2003/0162949; 2004/0013637;2003/0228274; 2003/0220447; 2003/0158333; 2003/0143596; 2003/0114647;2003/0105275; 2003/0105224; 2003/0023023; 2002/0156047; 2002/0099133;2002/0086939; 2002/0082345; 2002/0072573; 2002/0052430; 2002/0040076;2002/0037949; 2002/0002250; 2001/0056171; 2001/0044526; 2001/0027217;2001/0021763; U.S. Pat. Nos. 6,646,110; 5,824,778; 5,476,653; 5,219,564;5,629,384; 5,736,625; 4,902,502; 5,281,698; 5,122,614; 5,473,034;5,516,673; 5,382,657; 6,552,167; 6,610,281; 6,515,100; 6,461,603;6,436,386; 6,214,966; 5,990,237; 5,900,461; 5,739,208; 5,672,662;5,446,090; 5,808,096; 5,612,460; 5,324,844; 5,252,714; 6,420,339;6,201,072; 6,451,346; 6,306,821; 5,559,213; 5,612,460; 5,747,646;5,834,594; 5,849,860; 5,980,948; 6,004,573; 6,129,912; WO 97/32607, EP229,108, EP 402,378, WO 92/16555, WO 94/04193, WO 94/14758, WO 94/17039,WO 94/18247, WO 94/28024, WO 95/00162, WO 95/11924, WO 95/13090, WO95/33490, WO 96/00080, WO 97/18832, WO 98/41562, WO 98/48837, WO99/32134, WO 99/32139, WO 99/32140, WO 96/40791, WO 98/32466, WO95/06058, EP 439 508, WO 97/03106, WO 96/21469, WO 95/13312, EP 921 131,WO 98/05363, EP 809 996, WO 96/41813, WO 96/07670, EP 605 963, EP 510356, EP 400 472, EP 183 503 and EP 154 316, which are incorporated byreference herein. Any of the PEG molecules described herein may be usedin any form, including but not limited to, single chain, branched chain,multiarm chain, single functional, bi-functional, multi-functional, orany combination thereof.

Enhancing Affinity for Serum Albumin

Various molecules can also be fused to the hGH polypeptides of theinvention to modulate the half-life of hGH polypeptides in serum. Insome embodiments, molecules are linked or fused to hGH polypeptides ofthe invention to enhance affinity for endogenous serum albumin in ananimal.

For example, in some cases, a recombinant fusion of a hGH polypeptideand an albumin binding sequence is made. Exemplary albumin bindingsequences include, but are not limited to, the albumin binding domainfrom streptococcal protein G (see. e.g., Makrides et al., J. Pharmacol.Exp. Ther. 277:534-542 (1996) and Sjolander et al., J. Immunol. Methods201:115-123 (1997)), or albumin-binding peptides such as those describedin, e.g., Dennis, et al., J. Biol. Chem. 277:35035-35043 (2002).

In other embodiments, the hGH polypeptides of the present invention areacylated with fatty acids. In some cases, the fatty acids promotebinding to serum albumin. See, e.g., Kurtzhals, et al., Biochem. J.312:725-731 (1995).

In other embodiments, the hGH polypeptides of the invention are fuseddirectly with serum albumin (including but not limited to, human serumalbumin). Those of skill in the art will recognize that a wide varietyof other molecules can also be linked to hGH in the present invention tomodulate binding to serum albumin or other serum components.

X. Glycosylation of hGH Polypeptides

The invention includes hGH polypeptides incorporating one or morenon-naturally encoded amino acids bearing saccharide residues. Thesaccharide residues may be either natural (including but not limited to,N-acetylglucosamine) or non-natural (including but not limited to,3-fluorogalactose). The saccharides may be linked to the non-naturallyencoded amino acids either by an N- or O-linked glycosidic linkage(including but not limited to, N-acetylgalactose-L-serine) or anon-natural linkage (including but not limited to, an oxime or thecorresponding C- or S-linked glycoside).

The saccharide (including but not limited to, glycosyl) moieties can beadded to hGH polypeptides either in vivo or in vitro. In someembodiments of the invention, a hGH polypeptide comprising acarbonyl-containing non-naturally encoded amino acid is modified with asaccharide derivatized with an aminooxy group to generate thecorresponding glycosylated polypeptide linked via an oxime linkage. Onceattached to the non-naturally encoded amino acid, the saccharide may befurther elaborated by treatment with glycosyltransferases and otherenzymes to generate an oligosaccharide bound to the hGH polypeptide.See, e.g., H. Liu, et al. J. Am. Chem. Soc. 125: 1702-1703 (2003).

In some embodiments of the invention, a hGH polypeptide comprising acarbonyl-containing non-naturally encoded amino acid is modifieddirectly with a glycan with defined structure prepared as an aminooxyderivative. One skilled in the art will recognize that otherfunctionalities, including azide, alkyne, hydrazide, hydrazine, andsemicarbazide, can be used to link the saccharide to the non-naturallyencoded amino acid.

In some embodiments of the invention, a hGH polypeptide comprising anazide or alkynyl-containing non-naturally encoded amino acid can then bemodified by, including but not limited to, a Huisgen [3+2] cycloadditionreaction with, including but not limited to, alkynyl or azidederivatives, respectively. This method allows for proteins to bemodified with extremely high selectivity.

XI. GH Supergene Family Member Dimers and Multimers

The present invention also provides for GH supergene family membercombinations (including but not limited to hGH) homodimers,heterodimers, homomultimers, or heteromultimers (i.e., trimers,tetramers, etc.) where a GH supergene family member polypeptide such ashGH containing one or more non-naturally encoded amino acids is bound toanother GH supergene family member or variant thereof or any otherpolypeptide that is a non-GH supergene family member or variant thereof,either directly to the polypeptide backbone or via a linker. Due to itsincreased molecular weight compared to monomers, the GH supergene familymember, such as hGH, dimer or multimer conjugates may exhibit new ordesirable properties, including but not limited to differentpharmacological, pharmacokinetic, pharmacodynamic, modulated therapeutichalf-life, or modulated plasma half-life relative to the monomeric GHsupergene family member. In some embodiments, the GH supergene familymember, such as hGH, dimers of the invention will modulate thedimerization of the GH supergene family member receptor. In otherembodiments, the GH supergene family member dimers or multimers of thepresent invention will act as a GH supergene family member receptorantagonist, agonist, or modulator.

In some embodiments, one or more of the hGH molecules present in a hGHcontaining dimer or multimer comprises a non-naturally encoded aminoacid linked to a water soluble polymer that is present within the SiteII binding region. As such, each of the hGH molecules of the dimer ormultimer are accessible for binding to the hGH polypeptide receptor viathe Site I interface but are unavailable for binding to a second hGHpolypeptide receptor via the Site II interface. Thus, the hGHpolypeptide dimer or multimer can engage the Site I binding sites ofeach of two distinct hGH polypeptide receptors but, as the hGH moleculeshave a water soluble polymer attached to a non-genetically encoded aminoacid present in the Site II region, the hGH polypeptide receptors cannotengage the Site II region of the hGH polypeptide ligand and the dimer ormultimer acts as a hGH polypeptide antagonist. In some embodiments, oneor more of the hGH molecules present in a hGH polypeptide containingdimer or multimer comprises a non-naturally encoded amino acid linked toa water soluble polymer that is present within the Site I bindingregion, allowing binding to the Site II region. Alternatively, in someembodiments one or more of the hGH molecules present in a hGHpolypeptide containing dimer or multimer comprises a non-naturallyencoded amino acid linked to a water soluble polymer that is present ata site that is not within the Site I or Site II binding region, suchthat both are available for binding. In some embodiments a combinationof hGH molecules is used having Site I, Site II, or both available forbinding. A combination of hGH molecules wherein at least one has Site Iavailable for binding, and at least one has Site II available forbinding may provide molecules having a desired activity or property. Inaddition, a combination of hGH molecules having both Site I and Site IIavailable for binding may produce a super-agonist hGH molecule.

In some embodiments, the GH supergene family member polypeptides arelinked directly, including but not limited to, via an Asn-Lys amidelinkage or Cys-Cys disulfide linkage. In some embodiments, the linked GHsupergene family member polypeptides, and/or the linked non-GH supergenefamily member, will comprise different non-naturally encoded amino acidsto facilitate dimerization, including but not limited to, an alkyne inone non-naturally encoded amino acid of a first hGH polypeptide and anazide in a second non-naturally encoded amino acid of a second GHsupergene family member polypeptide will be conjugated via a Huisgen[3+2] cycloaddition. Alternatively, a first GH supergene family member,and/or the linked non-GH supergene family member, polypeptide comprisinga ketone-containing non-naturally encoded amino acid can be conjugatedto a second GH supergene family member polypeptide comprising ahydroxylamine-containing non-naturally encoded amino acid and thepolypeptides are reacted via formation of the corresponding oxime.

Alternatively, the two GH supergene family member polypeptides, and/orthe linked non-GH supergene family member, are linked via a linker. Anyhetero- or homo-bifunctional linker can be used to link the two GHsupergene family member, and/or the linked non-GH supergene familymember, polypeptides, which can have the same or different primarysequence. In some cases, the linker used to tether the GH supergenefamily member, and/or the linked non-GH supergene family member,polypeptides together can be a bifunctional PEG reagent.

In some embodiments, the invention provides water-soluble bifunctionallinkers that have a dumbbell structure that includes: a) an azide, analkyne, a hydrazine, a hydrazide, a hydroxylamine, or acarbonyl-containing moiety on at least a first end of a polymerbackbone; and b) at least a second functional group on a second end ofthe polymer backbone. The second functional group can be the same ordifferent as the first functional group. The second functional group, insome embodiments, is not reactive with the first functional group. Theinvention provides, in some embodiments, water-soluble compounds thatcomprise at least one arm of a branched molecular structure. Forexample, the branched molecular structure can be dendritic.

In some embodiments, the invention provides multimers comprising one ormore GH supergene family member, such as hGH, formed by reactions withwater soluble activated polymers that have the structure:R—(CH₂CH₂O)_(n)—O—(CH₂)_(m)—Xwherein n is from about 5 to 3,000, m is 2-10, X can be an azide, analkyne, a hydrazine, a hydrazide, an aminooxy group, a hydroxylamine, aacetyl, or carbonyl-containing moiety, and R is a capping group, afunctional group, or a leaving group that can be the same or differentas X. R can be, for example, a functional group selected from the groupconsisting of hydroxyl, protected hydroxyl, alkoxyl,N-hydroxysuccinimidyl ester, 1-benzotriazolyl ester,N-hydroxysuccinimidyl carbonate, 1-benzotriazolyl carbonate, acetal,aldehyde, aldehyde hydrates, alkenyl, acrylate, methacrylate,acrylamide, active sulfone, amine, aminooxy, protected amine, hydrazide,protected hydrazide, protected thiol, carboxylic acid, protectedcarboxylic acid, isocyanate, isothiocyanate, maleimide, vinylsulfone,dithiopyridine, vinylpyridine, iodoacetamide, epoxide, glyoxals, diones,mesylates, tosylates, and tresylate, alkene, and ketone.XII. Measurement of hGH Polypeptide Activity and Affinity of hGHPolypeptide for the hGH Polypeptide Receptor

The hGH receptor can be prepared as described in McFarland et al.,Science, 245: 494-499 (1989) and Leung, D., et al., Nature, 330:537-543(1987). hGH polypeptide activity can be determined using standard invitro or in vivo assays. For example, cell lines that proliferate in thepresence of hGH (e.g., a cell line expressing the hGH receptor or alactogenic receptor) can be used to monitor hGH receptor binding. See,e.g., Clark, R., et al., J. Biol. Chem. 271(36):21969 (1996); Wada, etal., Mol. Endocrinol. 12:146-156 (1998); Gout, P. W., et al. Cancer Res.40, 2433-2436 (1980); WO 99/03887. For a non-PEGylated hGH polypeptidecomprising a non-natural amino acid, the affinity of the hormone for itsreceptor can be measured by using a BIAcore™ biosensor (Pharmacia). See,e.g., U.S. Pat. No. 5,849,535; Spencer, S. A., et al., J. Biol. Chem.,263:7862-7867 (1988). In vivo animal models for testing hGH activityinclude those described in, e.g., Clark et al., J. Biol. Chem.271(36):21969-21977 (1996). Assays for dimerization capability of hGHpolypeptides comprising one or more non-naturally encoded amino acidscan be conducted as described in Cunningham, B., et al., Science,254:821-825 (1991) and Fuh, G., et al., Science, 256:1677-1680 (1992).All references and patents cited are incorporated by reference herein.

The above compilation of references for assay methodologies is notexhaustive, and those skilled in the art will recognize other assaysuseful for testing for the desired end result.

XIII. Measurement of Potency, Functional In Vivo Half-Life, andPharmacokinetic Parameters

An important aspect of the invention is the prolonged biologicalhalf-life that is obtained by construction of the hGH polypeptide withor without conjugation of the polypeptide to a water soluble polymermoiety. The rapid decrease of hGH polypeptide serum concentrations hasmade it important to evaluate biological responses to treatment withconjugated and non-conjugated hGH polypeptide and variants thereof.Preferably, the conjugated and non-conjugated hGH polypeptide andvariants thereof of the present invention have prolonged serumhalf-lives also after i.v. administration, making it possible to measureby, e.g. ELISA method or by a primary screening assay. ELISA or RIA kitsfrom either BioSource International (Camarillo, Calif.) or DiagnosticSystems Laboratories (Webster, Tex.) may be used. Measurement of in vivobiological half-life is carried out as described herein.

The potency and functional in vivo half-life of an hGH polypeptidecomprising a non-naturally encoded amino acid can be determinedaccording to the protocol described in Clark, R., et al., J. Biol. Chem.271, 36, 21969-21977 (1996).

Pharmacokinetic parameters for a hGH polypeptide comprising anon-naturally encoded amino acid can be evaluated in normalSprague-Dawley male rats (N=5 animals per treatment group). Animals willreceive either a single dose of 25 ug/rat iv or 50 ug/rat sc, andapproximately 5-7 blood samples will be taken according to a pre-definedtime course, generally covering about 6 hours for a hGH polypeptidecomprising a non-naturally encoded amino acid not conjugated to a watersoluble polymer and about 4 days for a hGH polypeptide comprising anon-naturally encoded amino acid and conjugated to a water solublepolymer. Pharmacokinetic data for hGH polypeptides is well-studied inseveral species and can be compared directly to the data obtained forhGH polypeptides comprising a non-naturally encoded amino acid. SeeMordenti J., et al., Pharm. Res. 8(11):1351-59 (1991) for studiesrelated to hGH.

The specific activity of hGH polypeptides in accordance with thisinvention can be determined by various assays known in the art. Thebiological activity of the hGH polypeptide muteins, or fragmentsthereof, obtained and purified in accordance with this invention can betested by methods described or referenced herein or known to thoseskilled in the art.

XIV. Administration and Pharmaceutical Compositions

The polypeptides or proteins of the invention (including but not limitedto, hGH, synthetases, proteins comprising one or more unnatural aminoacid, etc.) are optionally employed for therapeutic uses, including butnot limited to, in combination with a suitable pharmaceutical carrier.Such compositions, for example, comprise a therapeutically effectiveamount of the compound, and a pharmaceutically acceptable carrier orexcipient. Such a carrier or excipient includes, but is not limited to,saline, buffered saline, dextrose, water, glycerol, ethanol, and/orcombinations thereof. The formulation is made to suit the mode ofadministration. In general, methods of administering proteins are wellknown in the art and can be applied to administration of thepolypeptides of the invention.

Therapeutic compositions comprising one or more polypeptide of theinvention are optionally tested in one or more appropriate in vitroand/or in vivo animal models of disease, to confirm efficacy, tissuemetabolism, and to estimate dosages, according to methods well known inthe art. In particular, dosages can be initially determined by activity,stability or other suitable measures of unnatural herein to naturalamino acid homologues (including but not limited to, comparison of a hGHpolypeptide modified to include one or more unnatural amino acids to anatural amino acid hGH polypeptide), i.e., in a relevant assay.

Administration is by any of the routes normally used for introducing amolecule into ultimate contact with blood or tissue cells. The unnaturalamino acid polypeptides of the invention are administered in anysuitable manner, optionally with one or more pharmaceutically acceptablecarriers. Suitable methods of administering such polypeptides in thecontext of the present invention to a patient are available, and,although more than one route can be used to administer a particularcomposition, a particular route can often provide a more immediate andmore effective action or reaction than another route.

Pharmaceutically acceptable carriers are determined in part by theparticular composition being administered, as well as by the particularmethod used to administer the composition. Accordingly, there is a widevariety of suitable formulations of pharmaceutical compositions of thepresent invention.

Polypeptide compositions can be administered by a number of routesincluding, but not limited to oral, intravenous, intraperitoneal,intramuscular, transdermal, subcutaneous, topical, sublingual, or rectalmeans. Compositions comprising non-natural amino acid polypeptides,modified or unmodified, can also be administered via liposomes. Suchadministration routes and appropriate formulations are generally knownto those of skill in the art.

The hGH polypeptide comprising a non-natural amino acid, alone or incombination with other suitable components, can also be made intoaerosol formulations (i.e., they can be “nebulized”) to be administeredvia inhalation. Aerosol formulations can be placed into pressurizedacceptable propellants, such as dichlorodifluoromethane, propane,nitrogen, and the like.

Formulations suitable for parenteral administration, such as, forexample, by intraarticular (in the joints), intravenous, intramuscular,intradermal, intraperitoneal, and subcutaneous routes, include aqueousand non-aqueous, isotonic sterile injection solutions, which can containantioxidants, buffers, bacteriostats, and solutes that render theformulation isotonic with the blood of the intended recipient, andaqueous and non-aqueous sterile suspensions that can include suspendingagents, solubilizers, thickening agents, stabilizers, and preservatives.The formulations of packaged nucleic acid can be presented in unit-doseor multi-dose sealed containers, such as ampules and vials.

Parenteral administration and intravenous administration are preferredmethods of administration. In particular, the routes of administrationalready in use for natural amino acid homologue therapeutics (includingbut not limited to, those typically used for EPO, GH, G-CSF, GM-CSF,IFNs, interleukins, antibodies, and/or any other pharmaceuticallydelivered protein), along with formulations in current use, providepreferred routes of administration and formulation for the polypeptidesof the invention.

The dose administered to a patient, in the context of the presentinvention, is sufficient to have a beneficial therapeutic response inthe patient over time, or, including but not limited to, to inhibitinfection by a pathogen, or other appropriate activity, depending on theapplication. The dose is determined by the efficacy of the particularvector, or formulation, and the activity, stability or serum half-lifeof the unnatural amino acid polypeptide employed and the condition ofthe patient, as well as the body weight or surface area of the patientto be treated. The size of the dose is also determined by the existence,nature, and extent of any adverse side-effects that accompany theadministration of a particular vector, formulation, or the like in aparticular patient.

In determining the effective amount of the vector or formulation to beadministered in the treatment or prophylaxis of disease (including butnot limited to, cancers, inherited diseases, diabetes, AIDS, or thelike), the physician evaluates circulating plasma levels, formulationtoxicities, progression of the disease, and/or where relevant, theproduction of anti-unnatural amino acid polypeptide antibodies.

The dose administered, for example, to a 70 kilogram patient, istypically in the range equivalent to dosages of currently-usedtherapeutic proteins, adjusted for the altered activity or serumhalf-life of the relevant composition. The vectors of this invention cansupplement treatment conditions by any known conventional therapy,including antibody administration, vaccine administration,administration of cytotoxic agents, natural amino acid polypeptides,nucleic acids, nucleotide analogues, biologic response modifiers, andthe like.

For administration, formulations of the present invention areadministered at a rate determined by the LD-50 or ED-50 of the relevantformulation, and/or observation of any side-effects of the unnaturalamino acids at various concentrations, including but not limited to, asapplied to the mass and overall health of the patient. Administrationcan be accomplished via single or divided doses.

If a patient undergoing infusion of a formulation develops fevers,chills, or muscle aches, he/she receives the appropriate dose ofaspirin, ibuprofen, acetaminophen or other pain/fever controlling drug.Patients who experience reactions to the infusion such as fever, muscleaches, and chills are premedicated 30 minutes prior to the futureinfusions with either aspirin, acetaminophen, or, including but notlimited to, diphenhydramine. Meperidine is used for more severe chillsand muscle aches that do not quickly respond to antipyretics andantihistamines. Cell infusion is slowed or discontinued depending uponthe severity of the reaction.

Human hGH polypeptides of the invention can be administered directly toa mammalian subject. Administration is by any of the routes normallyused for introducing hGH polypeptide to a subject. The hGH polypeptidecompositions according to embodiments of the present invention includethose suitable for oral, rectal, topical, inhalation (including but notlimited to, via an aerosol), buccal (including but not limited to,sub-lingual), vaginal, parenteral (including but not limited to,subcutaneous, intramuscular, intradermal, intraarticular, intrapleural,intraperitoneal, inracerebral, intraarterial, or intravenous), topical(i.e., both skin and mucosal surfaces, including airway surfaces) andtransdermal administration, although the most suitable route in anygiven case will depend on the nature and severity of the condition beingtreated. Administration can be either local or systemic. Theformulations of compounds can be presented in unit-dose or multi-dosesealed containers, such as ampoules and vials. hGH polypeptides of theinvention can be prepared in a mixture in a unit dosage injectable form(including but not limited to, solution, suspension, or emulsion) with apharmaceutically acceptable carrier. hGH polypeptides of the inventioncan also be administered by continuous infusion (using, including butnot limited to, minipumps such as osmotic pumps), single bolus orslow-release depot formulations.

Formulations suitable for administration include aqueous and non-aqueoussolutions, isotonic sterile solutions, which can contain antioxidants,buffers, bacteriostats, and solutes that render the formulationisotonic, and aqueous and non-aqueous sterile suspensions that caninclude suspending agents, solubilizers, thickening agents, stabilizers,and preservatives. Solutions and suspensions can be prepared fromsterile powders, granules, and tablets of the kind previously described.

The pharmaceutical compositions of the invention may comprise apharmaceutically acceptable carrier. Pharmaceutically acceptablecarriers are determined in part by the particular composition beingadministered, as well as by the particular method used to administer thecomposition. Accordingly, there is a wide variety of suitableformulations of pharmaceutical compositions (including optionalpharmaceutically acceptable carriers, excipients, or stabilizers) of thepresent invention (see, e.g., Remington's Pharmaceutical Sciences,17^(th) ed. 1985)).

Suitable carriers include buffers containing phosphate, borate, HEPES,citrate, and other organic acids; antioxidants including ascorbic acid;low molecular weight (less than about 10 residues) polypeptides;proteins, such as serum albumin, gelatin, or immunoglobulins;hydrophilic polymers such as polyvinylpyrrolidone; amino acids such asglycine, glutamine, asparagine, arginine, or lysine; monosaccharides,disaccharides, and other carbohydrates, including glucose, mannose, ordextrins; chelating agents such as EDTA; divalent metal ions such aszinc, cobalt, or copper; sugar alcohols such as mannitol or sorbitol;salt-forming counter ions such as sodium; and/or nonionic surfactantssuch as Tween™, Pluronics™, or PEG.

hGH polypeptides of the invention, including those linked to watersoluble polymers such as PEG can also be administered by or as part ofsustained-release systems. Sustained-release compositions include,including but not limited to, semi-permeable polymer matrices in theform of shaped articles, including but not limited to, films, ormicrocapsules. Sustained-release matrices include from biocompatiblematerials such as poly(2-hydroxyethyl methacrylate) (Langer et al., J.Biomed. Mater. Res., 15: 167-277 (1981); Langer, Chem. Tech., 12: 98-105(1982), ethylene vinyl acetate (Langer et al., supra) orpoly-D-(−)-3-hydroxybutyric acid (EP 133,988), polylactides (polylacticacid) (U.S. Pat. No. 3,773,919; EP 58,481), polyglycolide (polymer ofglycolic acid), polylactide co-glycolide (copolymers of lactic acid andglycolic acid) polyanhydrides, copolymers of L-glutamic acid andgamma-ethyl-L-glutamate (U. Sidman et al., Biopolymers, 22, 547-556(1983), poly(ortho)esters, polypeptides, hyaluronic acid, collagen,chondroitin sulfate, carboxylic acids, fatty acids, phospholipids,polysaccharides, nucleic acids, polyamino acids, amino acids such asphenylalanine, tyrosine, isoleucine, polynucleotides, polyvinylpropylene, polyvinylpyrrolidone and silicone. Sustained-releasecompositions also include a liposomally entrapped compound. Liposomescontaining the compound are prepared by methods known per se: DE3,218,121; Epstein et al., Proc. Natl. Acad. Sci. U.S.A., 82: 3688-3692(1985); Hwang et al., Proc. Natl. Acad. Sci. U.S.A., 77: 4030-4034(1980); EP 52,322; EP 36,676; EP 88,046; EP 143,949; EP 142,641;Japanese Pat. Appln. 83-118008; U.S. Pat. Nos. 4,485,045 and 4,544,545;and EP 102,324. All references and patents cited are incorporated byreference herein.

Liposomally entrapped hGH polypeptides can be prepared by methodsdescribed in, e.g., DE 3,218,121; Epstein et al., Proc. Natl. Acad. Sci.U.S.A., 82: 3688-3692 (1985); Hwang et al., Proc. Natl. Acad. Sci.U.S.A., 77: 4030-4034 (1980); EP 52,322; EP 36,676; EP 88,046; EP143,949; EP 142,641; Japanese Pat. Appln. 83-118008; U.S. Pat. Nos.4,485,045 and 4,544,545; and EP 102,324. Composition and size ofliposomes are well known or able to be readily determined empirically byone skilled in the art. Some examples of liposomes as described in,e.g., Park J W, et al., Proc. Natl. Acad. Sci. USA 92:1327-1331 (1995);Lasic D and Papahadjopoulos D (eds): MEDICAL APPLICATIONS OF LIPOSOMES(1998); Drummond D C, et al., Liposomal drug delivery systems for cancertherapy, in Teicher B (ed): CANCER DRUG DISCOVERY AND DEVELOPMENT(2002); Park J W, et al., Clin. Cancer Res. 8:1172-1181 (2002); NielsenU B, et al., Biochim. Biophys. Acta 1591(1-3):109-118 (2002); Mamot C,et al., Cancer Res. 63: 3154-3161 (2003). All references and patentscited are incorporated by reference herein.

The dose administered to a patient in the context of the presentinvention should be sufficient to cause a beneficial response in thesubject over time. Generally, the total pharmaceutically effectiveamount of the hGH polypeptide of the present invention administeredparenterally per dose is in the range of about 0.01 μg/kg/day to about100 μg/kg, or about 0.05 mg/kg to about 1 mg/kg, of patient body weight,although this is subject to therapeutic discretion. The frequency ofdosing is also subject to therapeutic discretion, and may be morefrequent or less frequent than the commercially available hGHpolypeptide products approved for use in humans. Generally, a PEGylatedhGH polypeptide of the invention can be administered by any of theroutes of administration described above.

XV. Therapeutic Uses of hGH Polypeptides of the Invention

The hGH polypeptides of the invention are useful for treating a widerange of disorders.

The hGH agonist polypeptides of the invention may be useful, forexample, for treating growth deficiency, immune disorders, and forstimulating heart function. Individuals with growth deficienciesinclude, e.g., individuals with Turner's Syndrome, GH-deficientindividuals (including children), children who experience a slowing orretardation in their normal growth curve about 2-3 years before theirgrowth plate closes (sometimes known as “short normal children”), andindividuals where the insulin-like growth factor-I (IGF-I) response toGH has been blocked chemically (i.e., by glucocorticoid treatment) or bya natural condition such as in adult patients where the IGF-I responseto GH is naturally reduced.

An agonist hGH variant may act to stimulate the immune system of amammal by increasing its immune function, whether the increase is due toantibody mediation or cell mediation, and whether the immune system isendogenous to the host treated with the hGH polypeptide or istransplanted from a donor to the host recipient given the hGHpolypeptide (as in bone marrow transplants). “Immune disorders” includeany condition in which the immune system of an individual has a reducedantibody or cellular response to antigens than normal, including thoseindividuals with small spleens with reduced immunity due to drug (e.g.,chemotherapeutic) treatments. Examples individuals with immune disordersinclude, e.g., elderly patients, individuals undergoing chemotherapy orradiation therapy, individuals recovering from a major illness, or aboutto undergo surgery, individuals with AIDS, Patients with congenital andacquired B-cell deficiencies such as hypogammaglobulinemia, commonvaried agammaglobulinemia, and selective immunoglobulin deficiencies(e.g., IgA deficiency, patients infected with a virus such as rabieswith an incubation time shorter than the immune response of the patient;and individuals with hereditary disorders such as diGeorge syndrome.

hGH antagonist polypeptides of the invention may be useful for thetreatment of gigantism and acromegaly, diabetes and complications(diabetic retinopathy, diabetic neuropathy) arising from diabetes,vascular eye diseases (e.g., involving proliferativeneovascularization), nephropathy, and GH-responsive malignancies.

Vascular eye diseases include, e.g., retinopathy (caused by, e.g.,pre-maturity or sickle cell anemia) and macular degeneration.

GH-responsive malignancies include, e.g., Wilm's tumor, sarcomas (e.g.,osteogenic sarcoma), breast, colon, prostate, and thyroid cancer, andcancers of tissues that express GH receptor mRNA (i.e., placenta,thymus, brain, salivary gland, prostate, bone marrow, skeletal muscle,trachea, spinal cord, retina, lymph node and from Burkitt's lymphoma,colorectal carcinoma, lung carcinoma, lymphoblastic leukemia, andmelanoma).

Average quantities of the hGH may vary and in particular should be basedupon the recommendations and prescription of a qualified physician. Theexact amount of hGH is a matter of preference subject to such factors asthe exact type of condition being treated, the condition of the patientbeing treated, as well as the other ingredients in the composition.

EXAMPLES

The following examples are offered to illustrate, but not to limit theclaimed invention.

Example 1

This example describes one of the many potential sets of criteria forthe selection of preferred sites of incorporation of non-naturallyencoded amino acids into hGH.

This example demonstrates how preferred sites within the hGH polypeptidewere selected for introduction of a non-naturally encoded amino acid.The crystal structure 3HHR, composed of hGH complexed with two moleculesof the extracellular domain of receptor (hGHbp), was used to determinepreferred positions into which one or more non-naturally encoded aminoacids could be introduced. Other hGH structures (e.g. 1AXI) wereutilized to examine potential variation of primary and secondarystructural elements between crystal structure datasets. The coordinatesfor these structures are available from the Protein Data Bank (PDB)(Berstein et al. J. Mol. Biol. 1997, 112, pp 535) or via The ResearchCollaboratory for Structural Bioinformatics PDB available on the WorldWide Web at rcsb.org. The structural model 3HHR contains the entiremature 22 kDa sequence of hGH with the exception of residues 148-153 andthe C-terminal F191 residue which were omitted due to disorder in thecrystal. Two disulfide bridges are present, formed by C53 and C165 andC182 and C185. Sequence numbering used in this example is according tothe amino acid sequence of mature hGH (22 kDa variant) shown in SEQ IDNO:2.

The following criteria were used to evaluate each position of hGH forthe introduction of a non-naturally encoded amino acid: the residue (a)should not interfere with binding of either hGHbp based on structuralanalysis of 3HHR, 1AXI, and 1HWG (crystallographic structures of hGHconjugated with hGHbp monomer or dimer), b) should not be affected byalanine or homolog scanning mutagenesis (Cunningham et al. Science(1989) 244:1081-1085 and Cummingham et al. Science (1989)243:1330-1336), (c) should be surface exposed and exhibit minimal vander Waals or hydrogen bonding interactions with surrounding residues,(d) should be either deleted or variable in hGH variants (e.g. Tyr35,Lys38, Phe92, Lys140), (e) would result in conservative changes uponsubstitution with a non-naturally encoded amino acid and (f) could befound in either highly flexible regions (including but not limited to CDloop) or structurally rigid regions (including but not limited to HelixB). In addition, further calculations were performed on the hGHmolecule, utilizing the Cx program (Pintar et al. Bioinformatics, 18, pp980) to evaluate the extent of protrusion for each protein atom. As aresult, in some embodiments, one or more non-naturally encoded encodedamino acids are incorporated at, but not limited to, one or more of thefollowing positions of hGH: before position 1 (i.e. at the N-terminus),1, 2, 3, 4, 5, 8, 9, 11, 12, 15, 16, 19, 22, 29, 30, 32, 33, 34, 35, 36,37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 52, 55, 57, 59, 65,66, 69, 70, 71, 74, 88, 91, 92, 94, 95, 97, 98, 99, 100, 101, 102, 103,104, 105, 106, 107, 108, 109, 111, 112, 113, 115, 116, 119, 120, 122,123, 126, 127, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139,140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153,154, 155, 156, 158, 159, 161, 168, 172, 183, 184, 185, 186, 187, 188,189, 190, 191, 192 (i.e., at the carboxyl terminus of the protein) (SEQID NO: 2 or the corresponding amino acids in SEQ ID NO: 1 or 3).

In some embodiments, one or more non-naturally encoded amino acids aresubstituted at one or more of the following positions: 29, 30, 33, 34,35, 37, 39, 40, 49, 57, 59, 66, 69, 70, 71, 74, 88, 91, 92, 94, 95, 98,99, 101, 103, 107, 108, 111, 122, 126, 129, 130, 131, 133, 134, 135,136, 137, 139, 140, 141, 142, 143, 145, 147, 154, 155, 156, 159, 183,186, and 187 (SEQ ID NO: 2 or the corresponding amino acids of SEQ IDNO: 1 or 3).

In some embodiments, one or more non-naturally encoded amino acids aresubstituted at one or more of the following positions: 29, 33, 35, 37,39, 49, 57, 69, 70, 71, 74, 88, 91, 92, 94, 95, 98, 99, 101, 103, 107,108, 111, 129, 130, 131, 133, 134, 135, 136, 137, 139, 140, 141, 142,143, 145, 147, 154, 155, 156, 186, and 187 (SEQ ID NO: 2 or thecorresponding amino acids of SEQ ID NO: 1 or 3).

In some embodiments, one or more non-naturally encoded amino acids aresubstituted at one or more of the following positions: 35, 88, 91, 92,94, 95, 99, 101, 103, 111, 131, 133, 134, 135, 136, 139, 140, 143, 145,and 155 (SEQ ID NO: 2 or the corresponding amino acids of SEQ ID NO: 1or 3).

In some embodiments, one or more non-naturally encoded amino acids aresubstituted at one or more of the following positions: 30, 74, 103 (SEQID NO: 2 or the corresponding amino acids of SEQ ID NO: 1 or 3). In someembodiments, one or more non-naturally encoded amino acids aresubstituted at one or more of the following positions: 35, 92, 143, 145(SEQ ID NO: 2 or the corresponding amino acids of SEQ ID NO: 1 or 3).

In some embodiments, the non-naturally occurring amino acid at one ormore of these positions is linked to a water soluble polymer, includingbut not limited to, positions: before position 1 (i.e. at theN-terminus), 1, 2, 3, 4, 5, 8, 9, 11, 12, 15, 16, 19, 22, 29, 30, 32,33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 52,55, 57, 59, 65, 66, 69, 70, 71, 74, 88, 91, 92, 94, 95, 97, 98, 99, 100,101, 102, 103, 104, 105, 106, 107, 108, 109, 111, 112, 113, 115, 116,119, 120, 122, 123, 126, 127, 129, 130, 131, 132, 133, 134, 135, 136,137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150,151, 152, 153, 154, 155, 156, 158, 159, 161, 168, 172, 183, 184, 185,186, 187, 188, 189, 190, 191, 192 (i.e., at the carboxyl terminus of theprotein) (SEQ ID NO: 2 or the corresponding amino acids of SEQ ID NO: 1or 3). In some embodiments, the non-naturally occurring amino acid atone or more of these positions is linked to a water soluble polymer: 30,35, 74, 92, 103, 143, 145 (SEQ ID NO: 2 or the corresponding amino acidsof SEQ ID NO: 1 or 3). In some embodiments, the non-naturally occurringamino acid at one or more of these positions is linked to a watersoluble polymer: 35, 92, 143, 145 (SEQ ID NO: 2 or the correspondingamino acids of SEQ ID NO: 1 or 3).

Some sites for generation of an hGH antagonist include: 1, 2, 3, 4, 5,8, 9, 11, 12, 15, 16, 19, 22, 103, 109, 112, 113, 115, 116, 119, 120,123, 127, or an addition before position 1, or any combination thereof(SEQ ID NO: 2, or the corresponding amino acid in SEQ ID NO: 1, 3, orany other GH sequence). These sites were chosen utilizing criteria(c)-(e) of the agonist design. The antagonist design may also includesite-directed modifications of site I residues to increase bindingaffinity to hGHbp.

Example 2

This example details cloning and expression of a hGH polypeptideincluding a non-naturally encoded amino acid in E. coli. This examplealso describes one method to assess the biological activity of modifiedhGH polypeptides.

Methods for cloning hGH and fragments thereof are detailed in U.S. Pat.Nos. 4,601,980; 4,604,359; 4,634,677; 4,658,021; 4,898,830; 5,424,199;and 5,795,745, which are incorporated by reference herein. cDNA encodingthe full length hGH or the mature form of hGH lacking the N-terminalsignal sequence are shown in SEQ ID NO: 21 and SEQ ID NO: 22respectively.

An introduced translation system that comprises an orthogonal tRNA(O-tRNA) and an orthogonal aminoacyl tRNA synthetase (O-RS) is used toexpress hGH containing a non-naturally encoded amino acid. The O-RSpreferentially aminoacylates the O-tRNA with a non-naturally encodedamino acid. In turn the translation system inserts the non-naturallyencoded amino acid into hGH, in response to an encoded selector codon.TABLE 2 O-RS and O-tRNA sequences. SEQ ID NO: 4 M. jannaschiimtRNA_(CUA) ^(Tyr) tRNA SEQ ID NO: 5 HLAD03; an optimized ambersupressor tRNA tRNA SEQ ID NO: 6 HL325A; an optimized AGGA frameshiftsupressor tRNA tRNA SEQ ID NO: 7 Aminoacyl tRNA synthetase for theincorporation of p-azido-L-phenylalanine RS p-Az-PheRS(6) SEQ ID NO: 8Aminoacyl tRNA synthetase for the incorporation ofp-benzoyl-L-phenylalanine RS p-BpaRS(1) SEQ ID NO: 9 Aminoacyl tRNAsynthetase for the incorporation of propargyl-phenylalanine RSPropargyl-PheRS SEQ ID NO: 10 Aminoacyl tRNA synthetase for theincorporation of propargyl-phenylalanine RS Propargyl-PheRS SEQ ID NO:11 Aminoacyl tRNA synthetase for the incorporation ofpropargyl-phenylalanine RS Propargyl-PheRS SEQ ID NO: 12 Aminoacyl tRNAsynthetase for the incorporation of p-azido-phenylalanine RSp-Az-PheRS(1) SEQ ID NO: 13 Aminoacyl tRNA synthetase for theincorporation of p-azido-phenylalanine RS p-Az-PheRS(3) SEQ ID NO: 14Aminoacyl tRNA synthetase for the incorporation of p-azido-phenylalanineRS p-Az-PheRS(4) SEQ ID NO: 15 Aminoacyl tRNA synthetase for theincorporation of p-azido-phenylalanine RS p-Az-PheRS(2) SEQ ID NO: 16Aminoacyl tRNA synthetase for the incorporation ofp-acetyl-phenylalanine (LW1) RS SEQ ID NO: 17 Aminoacyl tRNA synthetasefor the incorporation of p-acetyl-phenylalanine (LW5) RS SEQ ID NO: 18Aminoacyl tRNA synthetase for the incorporation ofp-acetyl-phenylalanine (LW6) RS SEQ ID NO: 19 Aminoacyl tRNA synthetasefor the incorporation of p-azido-phenylalanine (AzPheRS-5) RS SEQ ID NO:20 Aminoacyl tRNA synthetase for the incorporation ofp-azido-phenylalanine (AzPheRS-6) RS

The transformation of E. coli with plasmids containing the modified hGHgene and the orthogonal aminoacyl tRNA synthetase/tRNA pair (specificfor the desired non-naturally encoded amino acid) allows thesite-specific incorporation of non-naturally encoded amino acid into thehGH polypeptide. The transformed E. coli, grown at 37° C. in mediacontaining between 0.01-100 mM of the particular non-naturally encodedamino acid, expresses modified hGH with high fidelity and efficiency.The His-tagged hGH containing a non-naturally encoded amino acid isproduced by the E. coli host cells as inclusion bodies or aggregates.The aggregates are solubilized and affinity purified under denaturingconditions in 6M guanidine HCl. Refolding is performed by dialysis at 4°C. overnight in 50 mM TRIS-HCl, pH8.0, 40 μM CuSO₄, and 2% (w/v)Sarkosyl. The material is then dialyzed against 20 mM TRIS-HCl, pH 8.0,100 mM NaCl, 2 mM CaCl₂, followed by removal of the His-tag. See Boisselet al., (1993) 268:15983-93. Methods for purification of hGH are wellknown in the art and are confirmed by SDS-PAGE, Western Blot analyses,or electrospray-ionization ion trap mass spectrometry and the like.

FIG. 6 is an SDS-PAGE of purified hGH polypeptides. The His-taggedmutant hGH proteins were purified using the ProBond Nickel-ChelatingResin (Invitrogen, Carlsbad, Calif.) via the standard His-tagged proteinpurification procedures provided by the manufacturer, followed by ananion exchange column prior to loading on the gel. Lane 1 shows themolecular weight marker, and lane 2 represents N-His hGH withoutincorporation of a non-natural amino acid. Lanes 3-10 contain N-His hGHmutants comprising the non-natural amino acid p-acetyl-phenylalanine ateach of the positions Y35, F92, Y11, G131, R134, K140, Y143, and K145,respectively.

To further assess the biological activity of modified hGH polypeptides,an assay measuring a downstream marker of hGH's interaction with itsreceptor was used. The interaction of hGH with its endogenously producedreceptor leads to the tyrosine phosphorylation of a signal transducerand activator of transcription family member, STAT5, in the human IM-9lymphocyte cell line. Two forms of STAT5, STAT5A and STAT5B wereidentified from an IM-9 cDNA library. See, e.g., Silva et al., Mol.Endocrinol. (1996) 10(5):508-518. The human growth hormone receptor onIM-9 cells is selective for human growth hormone as neither rat growthhormone nor human prolactin resulted in detectable STAT5phosphorylation. Importantly, rat GHR (L43R) extra cellular domain andthe G120R bearing hGH compete effectively against hGH stimulated pSTAT5phoshorylation.

IM-9 cells were stimulated with hGH polypeptides of the presentinvention. The human IM-9 lymphocytes were purchased from ATCC(Manassas, Va.) and grown in RPMI 1640 supplemented with sodiumpyruvate, penicillin, streptomycin (Invitrogen, Carlsbad, San Diego) and10% heat inactivated fetal calf serum (Hyclone, Logan, Utah). The IM-9cells were starved overnight in assay media (phenol-red free RPMI, 10 mMHepes, 1% heat inactivated charcoal/dextran treated FBS, sodiumpyruvate, penicillin and streptomycin) before stimulation with a12-point dose range of hGH polypeptides for 10 min at 37° C. Stimulatedcells were fixed with 1% formaldehyde before permeabilization with 90%ice-cold methanol for 1 hour on ice. The level of STAT5 phosphorylationwas detected by intra-cellular staining with a primary phospho-STAT5antibody (Cell Signaling Technology, Beverly, Mass.) at room temperaturefor 30 min followed by a PE-conjugated secondary antibody. Sampleacquisition was performed on the FACS Array with acquired data analyzedon the Flowjo software (Tree Star Inc., Ashland, Oreg.). EC₅₀ valueswere derived from dose response curves plotted with mean fluorescentintensity (MFI) against protein concentration utilizing SigmaPlot.

Table 3 below summarizes the IM-9 data generated with mutant hGHpolypeptides. Various hGH polypeptides with a non-natural amino acidsubstitution at different positions were tested with human IM-9 cells asdescribed. Specifically, FIG. 7, Panel A shows the IM-9 data for aHis-tagged hGH polypeptide, and FIG. 7, Panel B shows the IM-9 data forHis-tagged hGH comprising the non-natural amino acidp-acetyl-phenylalanine substitution for Y143. The same assay was used toassess biological activity of hGH polypeptides comprising a non-naturalamino acid that is PEGylated. TABLE 3 GH EC₅₀ (nM) GH EC₅₀ (nM) WHO WT0.4 ± 0.1 (n = 8) G120R >200,000 N-6His WT 0.6 ± 0.3 (n = 3)G120pAF >200,000 rat GH WT >200,000 G131pAF 0.8 ± 0.5 (n = 3) Y35pAF 0.7± 0.2 (n = 4) P133pAF 1.0 E88pAF 0.9 R134pAF 0.9 ± 0.3 (n = 4) Q91pAF2.0 ± 0.6 (n = 2) T135pAF 0.9 F92pAF 0.8 ± 0.4 (n = 9) G136pAF 1.4R94pAF 0.7 F139pAF 3.3 S95pAF 16.7 ± 1.0 (n = 2)  K140pAF 2.7 ± 0.9 (n =2) N99pAF 8.5 Y143pAF 0.8 ± 0.3 (n = 3) Y103pAF 130,000 K145pAF 0.6 ±0.2 (n = 3) Y111pAF 1.0 A155pAF 1.3

Example 3

This example details introduction of a carbonyl-containing amino acidand subsequent reaction with an aminooxy-containing PEG.

This Example demonstrates a method for the generation of a hGHpolypeptide that incorporates a ketone-containing non-naturally encodedamino acid that is subsequently reacted with an aminooxy-containing PEGof approximately 5,000 MW. Each of the residues 35, 88, 91, 92, 94, 95,99, 101, 103, 111, 120, 131, 133, 134, 135, 136, 139, 140, 143, 145, and155 identified according to the criteria of Example 1 (hGH) isseparately substituted with a non-naturally encoded amino acid havingthe following structure:

The sequences utilized for site-specific incorporation ofp-acetyl-phenylalanine into hGH are SEQ ID NO: 2 (hGH), and SEQ ID NO: 4(muttRNA, M. jannaschii mtRNA_(CUA) ^(Tyr)), and 16, 17 or 18 (TyrRSLW1, 5, or 6) described in Example 2 above.

Once modified, the hGH polypeptide variant comprising thecarbonyl-containing amino acid is reacted with an aminooxy-containingPEG derivative of the form:R-PEG(N)—O—(CH₂)_(n)—O—NH₂where R is methyl, n is 3 and N is approximately 5,000 MW. The purifiedhGH containing p-acetylphenylalanine dissolved at 10 mg/mL in 25 mM MES(Sigma Chemical, St. Louis, Mo.) pH 6.0, 25 mM Hepes (Sigma Chemical,St. Louis, Mo.) pH 7.0, or in 10 mM Sodium Acetate (Sigma Chemical, St.Louis, Mo.) pH 4.5, is reacted with a 10 to 100-fold excess ofaminooxy-containing PEG, and then stirred for 10-16 hours at roomtemperature (Jencks, W. J. Am. Chem. Soc. 1959, 81, pp 475). The PEG-hGHis then diluted into appropriate buffer for immediate purification andanalysis.

Example 4

Conjugation with a PEG consisting of a hydroxylamine group linked to thePEG via an amide linkage.

A PEG reagent having the following structure is coupled to aketone-containing non-naturally encoded amino acid using the proceduredescribed in Example 3:R-PEG(N)—O—(CH₂)₂—NH—C(O)(CH₂)_(n)—O—NH₂where R=methyl, n=4 and N is approximately 20,000 MW. The reaction,purification, and analysis conditions are as described in Example 3.

Example 5

This example details the introduction of two distinct non-naturallyencoded amino acids into hGH polypeptides.

This example demonstrates a method for the generation of a hGHpolypeptide that incorporates non-naturally encoded amino acidcomprising a ketone functionality at two positions among the followingresidues: E30, E74, Y103, K38, K41, K140, and K145. The hGH polypeptideis prepared as described in Examples 1 and 2, except that the suppressorcodon is introduced at two distinct sites within the nucleic acid.

Example 6

This example details conjugation of hGH polypeptide to ahydrazide-containing PEG and subsequent in situ reduction.

A hGH polypeptide incorporating a carbonyl-containing amino acid isprepared according to the procedure described in Examples 2 and 3. Oncemodified, a hydrazide-containing PEG having the following structure isconjugated to the hGH polypeptide:R-PEG(N)—O—(CH₂)₂—NH—C(O)(CH₂)_(n)—X—NH—NH₂where R=methyl, n=2 and N=10,000 MW and X is a carbonyl (C═O) group. Thepurified hGH containing p-acetylphenylalanine is dissolved at between0.1-10 mg/mL in 25 mM MES (Sigma Chemical, St. Louis, Mo.) pH 6.0, 25 mMHepes (Sigma Chemical, St. Louis, Mo.) pH 7.0, or in 10 mM SodiumAcetate (Sigma Chemical, St. Louis, Mo.) pH 4.5, is reacted with a 1 to100-fold excess of hydrazide-containing PEG, and the correspondinghydrazone is reduced in situ by addition of stock 1M NaCNBH₃ (SigmaChemical, St. Louis, Mo.), dissolved in H₂O, to a final concentration of10-50 mM. Reactions are carried out in the dark at 4° C. to RT for 18-24hours. Reactions are stopped by addition of 1 M Tris (Sigma Chemical,St. Louis, Mo.) at about pH 7.6 to a final Tris concentration of 50 mMor diluted into appropriate buffer for immediate purification.

Example 7

This example details introduction of an alkyne-containing amino acidinto a hGH polypeptide and derivatization with mPEG-azide.

The following residues, 35, 88, 91, 92, 94, 95, 99, 101, 131, 133, 134,135, 136, 140, 143, 145, and 155, are each substituted with thefollowing non-naturally encoded amino acid (hGH; SEQ ID NO: 2):

The sequences utilized for site-specific incorporation ofp-propargyl-tyrosine into hGH are SEQ ID NO: 2 (hGH), SEQ ID NO: 4(muttRNA, M. jannaschii mtRNA_(CUA) ^(Tyr)), and 9, or 11 described inExample 2 above. The hGH polypeptide containing the propargyl tyrosineis expressed in E. coli and purified using the conditions described inExample 3.

The purified hGH containing propargyl-tyrosine dissolved at between0.1-10 mg/mL in PB buffer (100 mM sodium phosphate, 0.15 M NaCl, pH=8)and a 10 to 1000-fold excess of an azide-containing PEG is added to thereaction mixture. A catalytic amount of CuSO₄ and Cu wire are then addedto the reaction mixture. After the mixture is incubated (including butnot limited to, about 4 hours at room temperature or 37° C., orovernight at 4° C.), H₂O is added and the mixture is filtered through adialysis membrane. The sample can be analyzed for the addition,including but not limited to, by similar procedures described in Example3.

In this Example, the PEG will have the following structure:R-PEG(N)—O—(CH₂)₂—NH—C(O)(CH₂)_(n)—N₃where R is methyl, n is 4 and N is 10,000 MW.

Example 8

This example details substitution of a large, hydrophobic amino acid ina hGH polypeptide with propargyl tyrosine.

A Phe, Trp or Tyr residue present within one the following regions ofhGH: 1-5 (N-terminus), 6-33 (A helix), 34-74 (region between A helix andB helix, the A-B loop), 75-96 (B helix), 97-105 (region between B helixand C helix, the B-C loop), 106-129 (C helix), 130-153 (region between Chelix and D helix, the C-D loop), 154-183 (D helix), 184-191(C-terminus) (SEQ ID NO: 2), is substituted with the followingnon-naturally encoded amino acid as described in Example 7:

Once modified, a PEG is attached to the hGH polypeptide variantcomprising the alkyne-containing amino acid. The PEG will have thefollowing structure:Me-PEG(N)—O—(CH₂)₂—N₃and coupling procedures would follow those in Example 7. This willgenerate a hGH polypeptide variant comprising a non-naturally encodedamino acid that is approximately isosteric with one of thenaturally-occurring, large hydrophobic amino acids and which is modifiedwith a PEG derivative at a distinct site within the polypeptide.

Example 9

This example details generation of a hGH polypeptide homodimer,heterodimer, homomultimer, or heteromultimer separated by one or morePEG linkers.

The alkyne-containing hGH polypeptide variant produced in Example 7 isreacted with a bifunctional PEG derivative of the form:N₃—(CH₂)_(n)—C(O)—NH—(CH₂)₂—O-PEG(N)—O—(CH₂)₂—NH—C(O)—(CH₂)_(n)—N₃where n is 4 and the PEG has an average MW of approximately 5,000, togenerate the corresponding hGH polypeptide homodimer where the two hGHmolecules are physically separated by PEG. In an analogous manner a hGHpolypeptide may be coupled to one or more other polypeptides to formheterodimers, homomultimers, or heteromultimers. Coupling, purification,and analyses will be performed as in Examples 7 and 3.

Example 10

This example details coupling of a saccharide moiety to a hGHpolypeptide.

One residue of the following is substituted with the non-natural encodedamino acid below: 29, 30, 33, 34, 35, 37, 39, 40, 49, 57, 59, 66, 69,70, 71, 74, 88, 91, 92, 94, 95, 98, 99, 101, 103, 107, 108, 111, 122,126, 129, 130, 131, 133, 134, 135, 136, 137, 139, 140, 141, 142, 143,145, 147, 154, 155, 156, 159, 183, 186, and 187 (hGH, SEQ ID NO: 2) asdescribed in Example 3.

Once modified, the hGH polypeptide variant comprising thecarbonyl-containing amino acid is reacted with a β-linked aminooxyanalogue of N-acetylglucosamine (GlcNAc). The hGH polypeptide variant(10 mg/mL) and the aminooxy saccharide (21 mM) are mixed in aqueous 100mM sodium acetate buffer (pH 5.5) and incubated at 37° C. for 7 to 26hours. A second saccharide is coupled to the first enzymatically byincubating the saccharide-conjugated hGH polypeptide (5 mg/mL) withUDP-galactose (16 mM) and β-1,4-galacytosyltransferase (0.4 units/mL) in150 mM HEPES buffer (pH 7.4) for 48 hours at ambient temperature(Schanbacher et al. J. Biol. Chem. 1970, 245, 5057-5061).

Example 11

This example details generation of a PEGylated hGH polypeptideantagonist.

One of the following residues, 1, 2, 3, 4, 5, 8, 9, 11, 12, 15, 16, 19,22, 103, 109, 112, 113, 115, 116, 119, 120, 123, or 127 (hGH, SEQ ID NO:2 or the corresponding amino acids in SEQ ID NO: 1 or 3), is substitutedwith the following non-naturally encoded amino acid as described inExample 3.

Once modified, the hGH polypeptide variant comprising thecarbonyl-containing amino acid will be reacted with anaminooxy-containing PEG derivative of the form:R-PEG(N)—O—(CH₂)_(n)—O—NH₂where R is methyl, n is 4 and N is 20,000 MW to generate a hGHpolypeptide antagonist comprising a non-naturally encoded amino acidthat is modified with a PEG derivative at a single site within thepolypeptide. Coupling, purification, and analyses are performed as inExample 3.

Example 12 Generation of a hGH Polypeptide Homodimer, Heterodimer,Homomultimer, or Heteromultimer in which the hGH Molecules are LinkedDirectly

A hGH polypeptide variant comprising the alkyne-containing amino acidcan be directly coupled to another hGH polypeptide variant comprisingthe azido-containing amino acid, each of which comprise non-naturallyencoded amino acid substitutions at the sites described in, but notlimited to, Example 10. This will generate the corresponding hGHpolypeptide homodimer where the two hGH polypeptide variants arephysically joined at the site II binding interface. In an analogousmanner a hGH polypeptide polypeptide may be coupled to one or more otherpolypeptides to form heterodimers, homomultimers, or heteromultimers.Coupling, purification, and analyses are performed as in Examples 3, 6,and 7.

Example 13

The polyalkylene glycol (P—OH) is reacted with the alkyl halide (A) toform the ether (B). In these compounds, n is an integer from one to nineand R′ can be a straight- or branched-chain, saturated or unsaturatedC1, to C20 alkyl or heteroalkyl group. R′ can also be a C3 to C7saturated or unsaturated cyclic alkyl or cyclic heteroalkyl, asubstituted or unsubstituted aryl or heteroaryl group, or a substitutedor unsubstituted alkaryl (the alkyl is a C1 to C20 saturated orunsaturated alkyl) or heteroalkaryl group. Typically, PEG-OH ispolyethylene glycol (PEG) or monomethoxy polyethylene glycol (mPEG)having a molecular weight of 800 to 40,000 Daltons (Da).

Example 14

mPEG-OH+Br—CH₂—C≡CH→mPEG-O—CH₂—C≡CH

mPEG-OH with a molecular weight of 20,000 Da (mPEG-OH 20 kDa; 2.0 g, 0.1mmol, Sunbio) was treated with NaH (12 mg, 0.5 mmol) in THF (35 mL). Asolution of propargyl bromide, dissolved as an 80% weight solution inxylene (0.56 mL, 5 mmol, 50 equiv., Aldrich), and a catalytic amount ofKI were then added to the solution and the resulting mixture was heatedto reflux for 2 hours. Water (1 mL) was then added and the solvent wasremoved under vacuum. To the residue was added CH₂Cl₂ (25 mL) and theorganic layer was separated, dried over anhydrous Na₂SO₄, and the volumewas reduced to approximately 2 mL. This CH₂Cl₂ solution was added todiethyl ether (150 mL) drop-wise. The resulting precipitate wascollected, washed with several portions of cold diethyl ether, and driedto afford propargyl-O-PEG.

Example 15

mPEG-OH+Br—(CH₂)₃—C≡CH→mPEG-O—(CH₂)₃—C≡CH

The mPEG-OH with a molecular weight of 20,000 Da (mPEG-OH 20 kDa; 2.0 g,0.1 mmol, Sunbio) was treated with NaH (12 mg, 0.5 mmol) in THF (35 mL).Fifty equivalents of 5-bromo-1-pentyne (0.53 mL, 5 mmol, Aldrich) and acatalytic amount of KI were then added to the mixture. The resultingmixture was heated to reflux for 16 hours. Water (1 mL) was then addedand the solvent was removed under vacuum. To the residue was addedCH₂Cl₂ (25 mL) and the organic layer was separated, dried over anhydrousNa₂SO₄, and the volume was reduced to approximately 2 mL. This CH₂Cl₂solution was added to diethyl ether (150 mL) drop-wise. The resultingprecipitate was collected, washed with several portions of cold diethylether, and dried to afford the corresponding alkyne. 5-chloro-1-pentynemay be used in a similar reaction.

Example 16

(1) m-HOCH₂C₆H₄OH+NaOH+Br—CH₂—C≡CH→m-HOCH₂C₆H₄O—CH₂—C≡CH(2) m-HOCH₂C₆H₄O—CH₂—C≡CH+MsCl+N(Et)₃ →m-MsOCH₂C₆H₄O—CH₂—C≡CH(3) m-MsOCH₂C₆H₄O—CH₂—C≡CH+LiBr→m-Br—CH₂C₆H₄O—CH₂—C≡CH(4) mPEG-OH+m-Br—CH₂C₆H₄O—CH₂—C≡CH→mPEG-O—CH₂—C₆H₄O—CH₂—C≡CH

To a solution of 3-hydroxybenzylalcohol (2.4 g, 20 mmol) in THF (50 mL)and water (2.5 mL) was first added powdered sodium hydroxide (1.5 g,37.5 mmol) and then a solution of propargyl bromide, dissolved as an 80%weight solution in xylene (3.36 mL, 30 mmol). The reaction mixture washeated at reflux for 6 hours. To the mixture was added 10% citric acid(2.5 mL) and the solvent was removed under vacuum. The residue wasextracted with ethyl acetate (3×15 mL) and the combined organic layerswere washed with saturated NaCl solution (10 mL), dried over MgSO₄ andconcentrated to give the 3-propargyloxybenzyl alcohol.

Methanesulfonyl chloride (2.5 g, 15.7 mmol) and triethylamine (2.8 mL,20 mmol) were added to a solution of compound 3 (2.0 g, 11.0 mmol) inCH₂Cl₂ at 0° C. and the reaction was placed in the refrigerator for 16hours. A usual work-up afforded the mesylate as a pale yellow oil. Thisoil (2.4 g, 9.2 mmol) was dissolved in THF (20 mL) and LiBr (2.0 g, 23.0mmol) was added. The reaction mixture was heated to reflux for 1 hourand was then cooled to room temperature. To the mixture was added water(2.5 mL) and the solvent was removed under vacuum. The residue wasextracted with ethyl acetate (3×15 mL) and the combined organic layerswere washed with saturated NaCl solution (10 mL), dried over anhydrousNa₂SO₄, and concentrated to give the desired bromide.

mPEG-OH 20 kDa (1.0 g, 0.05 mmol, Sunbio) was dissolved in THF (20 mL)and the solution was cooled in an ice bath. NaH (6 mg, 0.25 mmol) wasadded with vigorous stirring over a period of several minutes followedby addition of the bromide obtained from above (2.55 g, 11.4 mmol) and acatalytic amount of KI. The cooling bath was removed and the resultingmixture was heated to reflux for 12 hours. Water (1.0 mL) was added tothe mixture and the solvent was removed under vacuum. To the residue wasadded CH₂Cl₂ (25 mL) and the organic layer was separated, dried overanhydrous Na₂SO₄, and the volume was reduced to approximately 2 mL.Dropwise addition to an ether solution (150 mL) resulted in a whiteprecipitate, which was collected to yield the PEG derivative.

Example 17

mPEG-NH₂+X—C(O)—(CH₂)_(n)—C≡CR′→mPEG-NH—C(O)—(CH₂)_(n)—C≡CR′

The terminal alkyne-containing poly(ethylene glycol) polymers can alsobe obtained by coupling a poly(ethylene glycol) polymer containing aterminal functional group to a reactive molecule containing the alkynefunctionality as shown above. n is between 1 and 10. R′ can be H or asmall alkyl group from C1 to C4.

Example 18

(1) HO₂C—(CH₂)₂—C≡CH+NHS+DCC→NHSO—C(O)—(CH₂)₂—C≡CH(2) mPEG-NH₂+NHSO—C(O)—(CH₂)₂—C≡CH→mPEG-NH—C(O)—(CH₂)₂—C≡CH

4-pentynoic acid (2.943 g, 3.0 mmol) was dissolved in CH₂Cl₂ (25 mL).N-hydroxysuccinimide (3.80 g, 3.3 mmol) and DCC (4.66 g, 3.0 mmol) wereadded and the solution was stirred overnight at room temperature. Theresulting crude NHS ester 7 was used in the following reaction withoutfurther purification.

mPEG-NH₂ with a molecular weight of 5,000 Da (mPEG-NH₂, 1 g, Sunbio) wasdissolved in THF (50 mL) and the mixture was cooled to 4° C. NHS ester 7(400 mg, 0.4 mmol) was added portion-wise with vigorous stirring. Themixture was allowed to stir for 3 hours while warming to roomtemperature. Water (2 mL) was then added and the solvent was removedunder vacuum. To the residue was added CH₂Cl₂ (50 mL) and the organiclayer was separated, dried over anhydrous Na₂SO₄, and the volume wasreduced to approximately 2 mL. This CH₂Cl₂ solution was added to ether(150 mL) drop-wise. The resulting precipitate was collected and dried invacuo.

Example 19

This Example represents the preparation of the methane sulfonyl ester ofpoly(ethylene glycol), which can also be referred to as themethanesulfonate or mesylate of poly(ethylene glycol). The correspondingtosylate and the halides can be prepared by similar procedures.mPEG-OH+CH₃SO₂Cl+N(Et)₃→mPEG-O—SO₂CH₃→mPEG-N₃

The mPEG-OH (MW=3,400, 25 g, 10 mmol) in 150 mL of toluene wasazeotropically distilled for 2 hours under nitrogen and the solution wascooled to room temperature. 40 mL of dry CH₂Cl₂ and 2.1 mL of drytriethylamine (15 mmol) were added to the solution. The solution wascooled in an ice bath and 1.2 mL of distilled methanesulfonyl chloride(15 mmol) was added dropwise. The solution was stirred at roomtemperature under nitrogen overnight, and the reaction was quenched byadding 2 mL of absolute ethanol. The mixture was evaporated under vacuumto remove solvents, primarily those other than toluene, filtered,concentrated again under vacuum, and then precipitated into 100 mL ofdiethyl ether. The filtrate was washed with several portions of colddiethyl ether and dried in vacuo to afford the mesylate.

The mesylate (20 g, 8 mmol) was dissolved in 75 ml of THF and thesolution was cooled to 4° C. To the cooled solution was added sodiumazide (1.56 g, 24 mmol). The reaction was heated to reflux undernitrogen for 2 hours. The solvents were then evaporated and the residuediluted with CH₂Cl₂ (50 mL). The organic fraction was washed with NaClsolution and dried over anhydrous MgSO₄. The volume was reduced to 20 mland the product was precipitated by addition to 150 ml of cold dryether.

Example 20

(1) N₃—C₆H₄—CO₂H→N₃—C₆H₄CH₂OH(2) N₃—C₆H₄CH₂OH→Br—CH₂—C₆H₄—N₃(3) mPEG-OH+Br—CH₂—C₆H₄—N₃ →mPEG-O—CH₂—C₆H₄—N₃

4-azidobenzyl alcohol can be produced using the method described in U.S.Pat. No. 5,998,595, which is incorporated by reference herein.Methanesulfonyl chloride (2.5 g, 15.7 mmol) and triethylamine (2.8 mL,20 mmol) were added to a solution of 4-azidobenzyl alcohol (1.75 g, 11.0mmol) in CH₂Cl₂ at 0° C. and the reaction was placed in the refrigeratorfor 16 hours. A usual work-up afforded the mesylate as a pale yellowoil. This oil (9.2 mmol) was dissolved in THF (20 mL) and LiBr (2.0 g,23.0 mmol) was added. The reaction mixture was heated to reflux for 1hour and was then cooled to room temperature. To the mixture was addedwater (2.5 mL) and the solvent was removed under vacuum. The residue wasextracted with ethyl acetate (3×15 mL) and the combined organic layerswere washed with saturated NaCl solution (10 mL), dried over anhydrousNa₂SO₄, and concentrated to give the desired bromide.

mPEG-OH 20 kDa (2.0 g, 0.1 mmol, Sunbio) was treated with NaH (12 mg,0.5 mmol) in THF (35 mL) and the bromide (3.32 g, 15 mmol) was added tothe mixture along with a catalytic amount of KI. The resulting mixturewas heated to reflux for 12 hours. Water (1.0 mL) was added to themixture and the solvent was removed under vacuum. To the residue wasadded CH₂Cl₂ (25 mL) and the organic layer was separated, dried overanhydrous Na₂SO₄, and the volume was reduced to approximately 2 mL.Dropwise addition to an ether solution (150 mL) resulted in aprecipitate, which was collected to yield mPEG-O—CH₂—C₆H₄—N₃.

Example 21

NH₂—PEG-O—CH₂CH₂CO₂H+N₃—CH₂CH₂CO₂—NHS→N₃—CH₂CH₂—C(O)NH-PEG-O—CH₂CH₂CO₂H

NH₂—PEG-O—CH₂CH₂CO₂H (MW 3,400 Da, 2.0 g) was dissolved in a saturatedaqueous solution of NaHCO₃ (10 mL) and the solution was cooled to 0° C.3-azido-1-N-hydroxysuccinimido propionate (5 equiv.) was added withvigorous stirring. After 3 hours, 20 mL of H₂O was added and the mixturewas stirred for an additional 45 minutes at room temperature. The pH wasadjusted to 3 with 0.5 N H₂SO₄ and NaCl was added to a concentration ofapproximately 15 wt %. The reaction mixture was extracted with CH₂Cl₂(100 mL×3), dried over Na₂SO₄ and concentrated. After precipitation withcold diethyl ether, the product was collected by filtration and driedunder vacuum to yield the omega-carboxy-azide PEG derivative.

Example 22

mPEG-OMs+HC≡CLi→mPEG-O—CH₂—CH₂—C≡C—H

To a solution of lithium acetylide (4 equiv.), prepared as known in theart and cooled to −78° C. in THF, is added dropwise a solution ofmPEG-OMs dissolved in THF with vigorous stirring. After 3 hours, thereaction is permitted to warm to room temperature and quenched with theaddition of 1 mL of butanol. 20 mL of H₂O is then added and the mixturewas stirred for an additional 45 minutes at room temperature. The pH wasadjusted to 3 with 0.5 N H₂SO₄ and NaCl was added to a concentration ofapproximately 15 wt %. The reaction mixture was extracted with CH₂Cl₂(100 mL×3), dried over Na₂SO₄ and concentrated. After precipitation withcold diethyl ether, the product was collected by filtration and driedunder vacuum to yield the 1-(but-3-ynyloxy)-methoxypolyethylene glycol(mPEG).

Example 23

The azide- and acetylene-containing amino acids were incorporatedsite-selectively into proteins using the methods described in L. Wang,et al., (2001), Science 292:498-500, J. W. Chin et al., Science301:964-7 (2003)), J. W. Chin et al., (2002), Journal of the AmericanChemical Society 124:9026-9027; J. W. Chin, & P. G. Schultz, (2002),Chem Bio Chem 11:1135-1137; J. W. Chin, et al., (2002), PNAS UnitedStates of America 99:11020-11024: and, L. Wang, & P. G. Schultz, (2002),Chem. Comm., 1-10. Once the amino acids were incorporated, thecycloaddition reaction was carried out with 0.01 mM protein in phosphatebuffer (PB), pH 8, in the presence of 2 mM PEG derivative, 1 mM CuSO₄,and ˜1 mg Cu-wire for 4 hours at 37° C.

Example 24

This example describes the synthesis of p-Acetyl-D,L-phenylalanine (pAF)and m-PEG-hydroxylamine derivatives.

The racemic pAF was synthesized using the previously described procedurein Zhang, Z., Smith, B. A. C., Wang, L., Brock, A., Cho, C. & Schultz,P. G., Biochemistry, (2003) 42, 6735-6746.

To synthesize the m-PEG-hydroxylamine derivative, the followingprocedures were completed. To a solution of (N-t-Boc-aminooxy)aceticacid (0.382 g, 2.0 mmol) and 1,3-Diisopropylcarbodiimide (0.16 mL, 1.0mmol) in dichloromethane (DCM, 70 mL), which was stirred at roomtemperature (RT) for 1 hour, methoxy-polyethylene glycol amine(m-PEG-NH₂, 7.5 g, 0.25 mmol, Mt. 30 K, from BioVectra) andDiisopropylethylamine (0.1 mL, 0.5 mmol) were added. The reaction wasstirred at RT for 48 hours, and then was concentrated to about 100 mL.The mixture was added dropwise to cold ether (800 mL). Thet-Boc-protected product precipitated out and was collected by filtering,washed by ether 3×100 mL. It was further purified by re-dissolving inDCM (100 mL) and precipitating in ether (800 mL) twice. The product wasdried in vacuum yielding 7.2 g (96%), confirmed by NMR and Nihydrintest.

The deBoc of the protected product (7.0 g) obtained above was carriedout in 50% TFA/DCM (40 mL) at 0° C. for 1 hour and then at RT for 1.5hour. After removing most of TFA in vacuum, the TFA salt of thehydroxylamine derivative was converted to the HCl salt by adding 4N HClin dioxane (1 mL) to the residue. The precipitate was dissolved in DCM(50 mL) and re-precipitated in ether (800 mL). The final product (6.8 g,97%) was collected by filtering, washed with ether 3×100 mL, dried invacuum, stored under nitrogen. Other PEG (5K, 20K) hydroxylaminederivatives were synthesized using the same procedure.

Example 25

This example describes expression and purification methods used for hGHpolypeptides comprising a non-natural amino acid. Host cells have beentransformed with orthogonal tRNA, orthogonal aminoacyl tRNA synthetase,and hGH constructs.

A small stab from a frozen glycerol stock of the transformed DH10B(fis3)cells were first grown in 2 ml defined medium (glucose minimal mediumsupplemented with leucine, isoleucine, trace metals, and vitamins) with100 μg/ml ampicillin at 37° C. When the OD₆₀₀ reached 2-5, 60 μl wastransferred to 60 ml fresh defined medium with 100 μg/ml ampicillin andagain grown at 37° C. to an OD₆₀₀ of 2-5. 50 ml of the culture wastransferred to 2 liters of defined medium with 100 μg/ml ampicillin in a5 liter fermenter (Sartorius BBI). The fermenter pH was controlled at pH6.9 with potassium carbonate, the temperature at 37° C., the air flowrate at 51 pm, and foam with the polyalkylene defoamer KFO F119(Lubrizol). Stirrer speeds were automatically adjusted to maintaindissolved oxygen levels ≧30% and pure oxygen was used to supplement theair sparging if stirrer speeds reached their maximum value. After 8hours at 37° C., the culture was fed a 50× concentrate of the definedmedium at an exponentially increasing rate to maintain a specific growthrate of 0.15 hour⁻¹. When the OD₆₀₀ reached approximately 100, a racemicmixture of para-acetyl-phenylalanine was added to a final concentrationof 3.3 mM, and the temperature was lowered to 28° C. After 0.75 hour,isopropyl-b-D-thiogalactopyranoside was added to a final concentrationof 0.25 mM. Cells were grown an additional 8 hour at 28° C., pelleted,and frozen at −80° C. until further processing.

The His-tagged mutant hGH proteins were purified using the ProBondNickel-Chelating Resin (Invitrogen, Carlsbad, Calif.) via the standardHis-tagged protein purification procedures provided by Invitrogen'sinstruction manual, followed by an anion exchange column.

The purified hGH was concentrated to 8 mg/ml and buffer exchanged to thereaction buffer (20 mM sodium acetate, 150 mM NaCl, 1 mM EDTA, pH 4.0).MPEG-Oxyamine powder was added to the hGH solution at a 20:1 molar ratioof PEG:hGH. The reaction was carried out at 28° C. for 2 days withgentle shaking. The PEG-hGH was purified from un-reacted PEG and hGH viaan anion exchange column.

The quality of each PEGylated mutant hGH was evaluated by three assaysbefore entering animal experiments. The purity of the PEG-hGH wasexamined by running a 4-12% acrylamide NuPAGE Bis-Tris gel with MES SDSrunning buffer under non-reducing conditions (Invitrogen). The gels werestained with Coomassie blue. The PEG-hGH band was greater than 95% purebased on densitometry scan. The endotoxin level in each PEG-hGH wastested by a kinetic LAL assay using the KTA² kit from Charles RiverLaboratories (Wilmington, Mass.), and it was less than 5 EU per dose.The biological activity of the PEG-hGH was assessed with the IM-9 pSTAT5bioassay (mentioned in Example 2), and the EC₅₀ value was less than 15nM.

Example 26

This example describes methods for evaluating purification andhomogeneity of hGH polypeptides comprising a non-natural amino acid.

FIG. 8 is a SDS-PAGE of hGH polypeptides comprising a non-natural aminoacid at position 92. Lanes 3, 4, and 5 of the gel show hGH comprising ap-acetyl-phenylalanine at position 92 covalently linked to either a 5kDa, 20 kDa, or 30 kDa PEG molecule. Additional hGH polypeptidescomprising a non-natural amino acid that is PEGylated are shown FIG. 11.Five μg of each PEG-hGH protein was loaded onto each SDS-PAGE. FIG. 11,Panel A: Lane 1, molecular weight marker; lane 2, WHO rhGH referencestandard (2 μg); lanes 3 and 7, 30KPEG-F92pAF; lane 4, 30KPEG-Y35pAF;lane 5, 30KPEG-R134pAF; lane 6, 20 KPEG-R134pAF; lane 8, WHO rhGHreference standard (20 μg). FIG. 11, Panel B: Lane 9, molecular weightmarker, lane 10, WHO rhGH reference standard (2 μg); lane 11,30KPEG-F92pAF; lane 12, 30KPEG-K145pAF; lane 13, 30KPEG-Y143pAF; lane14, 30KPEG-G131pAF; lane 15, 30KPEG-F92pAF/G120R, lane 16 WHO rhGHreference standard (20 μg). FIG. 9 shows the biological activity ofPEGylated hGH polypeptides (5 kDa, 20 kDa, or 30 kDa PEG) in IM-9 cells;methods were performed as described in Example 2.

The purity of the hGH-PEG conjugate can be assessed by proteolyticdegradation (including but not limited to, trypsin cleavage) followed bymass spectrometry analysis. Pepinsky B., et al., J Pharmcol. & Exp.Ther. 297(3):1059-66 (2001). Methods for performing tryptic digests arealso described in the European Pharmacopoeia (2002) 4^(th) Edition, pp.1938). Modifications to the methods described were performed. Samplesare dialyzed overnight in 50 mM TRIS-HCl, pH 7.5. rhGH polypeptides wereincubated with trypsin (TPCK-treated trypsin, Worthington) at a massratio of 66:1 for 4 hours in a 37° C. water bath. The samples wereincubated on ice for several minutes to stop the digestion reaction andsubsequently maintained at 4° C. during HPLC analysis. Digested samples(˜200 μg) were loaded onto a 25×0.46 cm Vydac C-8 column (5-μm beadsize, 100 Å pore size) in 0.1% trifluoroacetic acid and eluted with agradient from 0 to 80% acetonitrile over 70 min at a flow rate of 1ml/min at 30° C. The elution of tryptic peptides was monitored byabsorbance at 214 nm.

FIG. 10, Panel A depicts the primary structure of hGH with the trypsincleavage sites indicated and the non-natural amino acid substitution,F92pAF, specified with an arrow (Figure modified from Becker et al.Biotechnol Appl Biochem. (1988) 10(4):326-337). Panel B showssuperimposed tryptic maps of peptides generated from a hGH polypeptidecomprising a non-naturally encoded amino acid that is PEGylated (30K PEGHis₆-F92pAF rhGH, labeled A), peptides generated from a hGH polypeptidecomprising a non-naturally encoded amino acid (His₆-F92pAF rhGH, labeledB), and peptides generated from wild type hGH (WHO rhGH, labeled C).Comparison of the tryptic maps of WHO rhGH and His₆-F92pAF rhGH revealsonly two peak shifts, peptide peak 1 and peptide peak 9, and theremaining peaks are identical. These differences are caused by theaddition of the His₆ on the N-terminus of the expressed His₆-F92pAFrhGH, resulting in peak 1 shifting; whereas the shift in peak 9 iscaused by the substitution of phenylalanine at residue 92 withp-acetyl-phenylalanine. Panel C—A magnification of peak 9 from Panel Bis shown. Comparison of the His₆-F92pAF and the 30K PEG His₆-F92pAF rhGHtryptic maps reveals the disappearance of peak 9 upon pegylation ofHis₆-F92pAF rhGH, thus confirming that modification is specific topeptide 9.

Example 27

This example describes a homodimer formed from two hGH polypeptides eachcomprising a non-natural amino acid.

FIG. 12 compares IM-9 assay results from a His-tagged hGH polypeptidecomprising a p-acetyl-phenylalanine substitution at position 92 with ahomodimer of this modified polypeptide joined with a linker that isbifunctional having functional groups and reactivity as described inExample 25 for PEGylation of hGH.

Example 28

This example describes a monomer and dimer hGH polypeptide that act as ahGH antagonist.

An hGH mutein in which a G120R substitution has been introduced intosite II is able to bind a single hGH receptor, but is unable to dimerizetwo receptors. The mutein acts as an hGH antagonist in vitro, presumablyby occupying receptor sites without activating intracellular signalingpathways (Fuh, G., et al., Science 256:1677-1680 (1992)). FIG. 13, PanelA shows IM-9 assay data measuring phosphorylation of pSTAT5 by hGH withthe G120R substitution. A hGH polypeptide with a non-natural amino acidincorporated at the same position (G120) resulted in a molecule thatalso acts as an hGH antagonist, as shown in FIG. 13, Panel B. A dimer ofthe hGH antagonist shown in FIG. 13, Panel B was constructed joined witha linker that is bifunctional having functional groups and reactivity asdescribed in Example 25 for PEGylation of hGH. FIG. 14 shows that thisdimer also lacks biological activity in the IM-9 assay.

Additional assays were performed comparing hGH polypeptide comprising aG120pAF substitution with a dimer of G120pAF modified hGH polypeptidesjoined by a PEG linker. WHO hGH induced phosphorylation of STAT5 wascompeted with a dose-response range of the monomer and the dimer joinedby a PEG linker. Surface receptor competition studies were alsoperformed showing that the monomer and the dimer compete with GH forcell surface receptor binding on IM-9 and rat GHR (L43R)/BAF3 cells. Thedimer acted as a more potent antagonist than the monomer. Table 4 showsthe data from these studies. TABLE 4 Rat GHR Cell line IM-9 IM-9(L43R)/BAF3 Inhibition of Surface receptor Surface receptor Assay pSTAT5competition competition IC₅₀ (nM) IC₅₀ (nM) IC₅₀ (nM) G120pAF monomer3.3 8.4 3.1 (G120pAF) dimer, 0.7 2.7 1.4 PEG linker

Example 29

This example details the measurement of hGH activity and affinity of hGHpolypeptides for the hGH receptor.

Cloning and purification of rat GH receptor The extracellular domain ofrat GH receptor (GHR ECD, amino acids S29-T238) was cloned into pET20bvector (Novagen) between Nde I and Hind III sites in frame withC-terminal 6H is tag. A mutation of L43 to R was introduced to furtherapproximate the human GH receptor binding site (Souza et al., Proc NatlAcad Sci USA. (1995) 92(4): 959-63). Recombinant protein was produced inBL21(DE3) E. coli cells (Novagen) by induction with 0.4 mM IPTG at 30°C. for 4-5 hours. After lysing the cells, the pellet was washed fourtimes by resuspending in a dounce with 30 mL of 50 mM Tris, pH 7.6, 100mM NaCl, 1 mM EDTA, 1% Triton X-100, and twice with the same bufferwithout Triton X-100. At this point inclusion bodies consisted of morethan 95% GHR ECD and were solubilized in 0.1M Tris, pH 11.5, 2M urea.Refolding was accomplished by means of passing an aliquot of theinclusion body solution through a S100 (Sigma) gel filtration column,equilibrated with 50 mM Tris, pH 7.8, 1 M L-arginine, 3.7 mM cystamine,6.5 mM cysteamine. Fractions containing soluble protein were combinedand dialyzed against 50 mM Tris, pH 7.6, 200 mM NaCl, 10% glycerol. Thesample was briefly centrifuged to remove any precipitate and incubatedwith an aliquot of Talon resin (Clontech), according to manufacturer'sinstructions. After washing the resin with 20 volumes of dialysis buffersupplemented with 5 mM imidazole, protein was eluted with 120 mMimidazole in dialysis buffer. Finally, the sample was dialyzed overnightagainst 50 mM Tris, pH 7.6, 30 mM NaCl, 1 mM EDTA, 10% glycerol,centrifuged briefly to remove any precipitate, adjusted to 20% glycerolfinal concentration, aliquoted and stored at −80 C. Concentration of theprotein was measured by OD(280) using calculated extinction coefficientof ε=65,700 M⁻¹*cm⁻¹.

Biocore™ Analysis of Binding of GH to GHR

Approximately 600-800 RUs of soluble GHR ECD was immobilized on aBiacore™ CM5 chip, using a standard amine-coupling procedure, asrecommended by the manufacturer. Even though a significant portion ofthe receptor was inactivated by this technique, it was foundexperimentally that this level of immobilization was sufficient toproduce maximal specific GH binding response of about 100-150 RUs, withno noticeable change in binding kinetics. See, e.g., Cunningham et al. JMol Biol. (1993) 234(3): 554-63 and Wells J A. Proc Natl Acad Sci USA(1996) 93(1): 1-6).

Various concentrations of wild type or mutant GH (0.1-300 nM) in HBS-EPbuffer (Biacore™, Pharmacia) were injected over the GHR surface at aflow rate of 40 μl/min for 4-5 minutes, and dissociation was monitoredfor 15 minutes post-injection. The surface was regenerated by a 15second pulse of 4.5M MgCl₂. Only a minimal loss of binding affinity(1-5%) was observed after at least 100 regeneration cycles. Referencecell with no receptor immobilized was used to subtract any buffer bulkeffects and non-specific binding.

Kinetic binding data obtained from GH titration experiments wasprocessed with BiaEvaluation 4.1 software (BIACORE™). “Bivalent analyte”association model provided satisfactory fit (chi² values generally below3), in agreement with proposed sequential 1:2 (GH:GHR) dimerization(Wells J A. Proc Natl Acad Sci USA (1996) 93(1): 1-6). Equilibriumdissociation constants (Kd) were calculated as ratios of individual rateconstants (k_(off)/k_(on)).

Table 5 indicates the binding parameters from Biacore™ using rat GHR ECD(L43R) immobilized on a CM5 chip. TABLE 5 GH k_(on), ×10,⁻⁵ 1/M*sk_(off), ×10⁴, 1/s K_(d), nM WHO WT 6.4 3.8 0.6 N-6His WT 9 5.6 0.6 ratGH WT 0.33 83 250 N12pAF 12.5 4.6 0.4 R16pAF 6.8 4.8 0.7 Y35pAF 7.8 5.30.7 E88pAF 6.8 5.4 0.8 Q91pAF 6.6 4.9 0.7 F92pAF 8.6 5.0 0.6 R94pAF 5.66.0 1.1 S95pAF 0.7 3.1 4.3 N99pAF 2.2 3.8 1.7 Y103pAF ˜0.06 ˜6 >100Y111pAF 8.4 4.8 0.6 G120R 2.2 22 10 G120pAF 1.1 23 20 G131pAF 6.0 5.30.9 P133pAF 6.4 4.9 0.8 R134pAF 8.4 5.8 0.7 T135pAF 7.2 4.5 0.6 G136pAF6.2 4.3 0.7 F139pAF 6.8 4.4 0.7 K140pAF 7.2 3.7 0.5 Y143pAF 7.8 6.7 0.9K145pAF 6.4 5.0 0.8 A155pAF 5.8 4.4 0.8 F92pAF-5KD PEG 6.2 2.3 0.4F92pAF-20KD PEG 1.7 1.8 1.1 F92pAF-30KD PEG 1.3 0.9 0.7 R134pAF-5KD PEG6.8 2.7 0.4 R134pAF-30KD PEG 0.7 1.7 2.4 Y35pAF-30KD PEG 0.9 0.7 0.7(G120pAF) dimer 0.4 1.5 3.4 (F92pAF) dimer 3.6 1.8 0.5GHR Stable Cell Lines

The IL-3 dependent mouse cell line, BAF3, was routinely passaged in RPMI1640, sodium pyruvate, penicillin, streptomycin, 10% heat-inactivatedfetal calf serum, 50 uM 2-mercaptoethanol and 10% WEHI-3 cell lineconditioned medium as source of IL-3. All cell cultures were maintainedat 37° C. in a humidified atmosphere of 5% CO₂.

The BAF3 cell line was used to establish the rat GHR (L43R) stable cellclone, 2E2-2B12-F4. Briefly, 1×10⁷ mid-confluent BAF3 cells wereelectroporated with 15 ug of linearized pcDNA3.1 plasmid containing thefull length rat GHR (L43R) cDNA. Transfected cells were allowed torecover for 48 hours before cloning by limiting dilution in mediacontaining 800 ug/ml G418 and 5 nM WHO hGH. GHR expressing transfectantswere identified by surface staining with antibody against human GHR (R&DSystems, Minneapolis, Minn.) and analyzed on a FACS Array (BDBiosciences, San Diego, Calif.). Transfectants expressing a good levelof GHR were then screened for proliferative activity against WHO hGH ina BrdU proliferation assay (as described below). Stably transfected ratGHR (L43R) cell clones were established upon two further rounds ofrepeated subcloning of desired transfectants in the presence of 1.2mg/ml G418 and 5 nM hGH with constant profiling for surface receptorexpression and proliferative capability. Cell clone, 2E2-2B12-F4, thusestablished is routinely maintained in BAF3 media plus 1.2 mg/ml G418 inthe absence of hGH.

Proliferation by BrdU Labeling

Serum starved rat GHR (L43R) expressing BAF3 cell line, 2E2-2B12-F4,were plated at a density of 5×10⁴ cells/well in a 96-well plate. Cellswere activated with a 12-point dose range of hGH proteins and labeled atthe same time with 50 uM BrdU (Sigma, St. Louis, Mo.). After 48 hours inculture, cells were fixed/permeabilized with 100 ul of BDcytofix/cytoperm solution (BD Biosciences) for 30 min at roomtemperature. To expose BrdU epitopes, fixed/permeablilized cells weretreated with 30 ug/well of DNase (Sigma) for 1 hour at 37° C.Immunofluorescent staining with APC-conjugated anti-BrdU antibody (BDBiosciences) enabled sample analysis on the FACS Array.

Table 6 shows the bioactivity of PEG hGH mutants as profiled on thepSTAT5 (IM-9) and BrdU proliferation assays. WHO hGH is expressed asunity for comparison between assays. TABLE 6 pSTAT5 EC₅₀ ProliferationEC₅₀ hGH (nM) (nM) WHO WT 1.0 1.0 Y35pAF 1.3 1.6 ± 0.8 (n = 3)Y35pAF-30KPEG 10 5.4 ± 2.8 (n = 4) Y35pAF-40KPEG 53.3 24.0 + 11.0 (n =3) F92pAF 2.2 ± 0.4 (n = 9) 1.4 ± 0.7 (n = 4) F92pAF-5KPEG 5.1 + 0.4 (n= 3) ND F92pAF-20KPEG 10.5 + 0.8 (n = 3)  ND F92pAF-30KPEG 8.8 ± 1.2 (n= 8) 4.1 ± 0.9 (n = 3) F92pAF/G120R >200,000 >200,000F92pAF/G120R- >200,000 >200,000 30KPEG G131pAF 2.3 ± 1.8 (n = 2) 2.1 ±1.1 (n = 3) G131pAF-30KPEG 23.8 ± 1.7 (n = 2)  4.6 ± 2.4 (n = 3) R134pAF1.1 ± 0.2 (n = 2) 1.7 ± 0.3 (n = 3) R134pAF-20KPEG 5.3 ND R134pAF-30KPEG11.3 ± 1.1 (n = 2)  2.5 ± 0.7 (n = 4) Y143pAF 1.6 ± 0.1 (n = 2) 1.8 ±0.6 (n = 2) Y143pAF-30KPEG 12.3 ± 0.9 (n = 2)  6.6 ± 2.7 (n = 3) K145pAF2.3 ± 0.5 (n = 2) 3.0 ± 1.4 (n = 2) K145pAF-30KPEG 20.6 ± 9.8 (n = 2) 5.3 ± 3.5 (n = 3)

Example 30

This example describes methods to measure in vitro and in vivo activityof PEGylated hGH.

Cell Binding Assays

Cells (3×10⁶) are incubated in duplicate in PBS/1% BSA (100 μl) in theabsence or presence of various concentrations (volume: 10 μl) ofunlabeled GH, hGH or GM-CSF and in the presence of ¹²⁵I-GH (approx.100,000 cpm or 1 ng) at 0° C. for 90 minutes (total volume: 120 μl).Cells are then resuspended and layered over 200 μl ice cold FCS in a 350μl plastic centrifuge tube and centrifuged (1000 g; 1 minute). Thepellet is collected by cutting off the end of the tube and pellet andsupernatant counted separately in a gamma counter (Packard).

Specific binding (cpm) is determined as total binding in the absence ofa competitor (mean of duplicates) minus binding (cpm) in the presence of100-fold excess of unlabeled GH (non-specific binding). The non-specificbinding is measured for each of the cell types used. Experiments are runon separate days using the same preparation of ¹²⁵I-GH and shoulddisplay internal consistency. ¹²⁵I-GH demonstrates binding to the GHreceptor-producing cells. The binding is inhibited in a dose dependentmanner by unlabeled natural GH or hGH, but not by GM-CSF or othernegative control. The ability of hGH to compete for the binding ofnatural ¹²⁵I-GH, similar to natural GH, suggests that the receptorsrecognize both forms equally well.

In Vivo Studies of PEGylated hGH

PEG-hGH, unmodified hGH and buffer solution are administered to mice orrats. The results will show superior activity and prolonged half life ofthe PEGylated hGH of the present invention compared to unmodified hGHwhich is indicated by significantly increased bodyweight.

Measurement of the In Vivo Half-Life of Conjugated and Non-ConjugatedhGH and Variants Thereof.

All animal experimentation was conducted in an AAALAC accreditedfacility and under protocols approved by the Institutional Animal Careand Use Committee of St. Louis University. Rats were housed individuallyin cages in rooms with a 12-hour light/dark cycle. Animals were providedaccess to certified Purina rodent chow 5001 and water ad libitum. Forhypophysectomized rats, the drinking water additionally contained 5%glucose.

Pharmacokinetic Studies

The quality of each PEGylated mutant hGH was evaluated by three assaysbefore entering animal experiments. The purity of the PEG-hGH wasexamined by running a 4-12% acrylamide NuPAGE Bis-Tris gel with MES SDSrunning buffer under non-reducing conditions (Invitrogen, Carlsbad,Calif.). The gels were stained with Coomassie blue. The PEG-hGH band wasgreater than 95% pure based on densitometry scan. The endotoxin level ineach PEG-hGH was tested by a kinetic LAL assay using the KTA² kit fromCharles River Laboratories (Wilmington, Mass.), and was less than 5 EUper dose. The biological activity of the PEG-hGH was assessed with theIM-9 pSTAT5 bioassay (described in Example 2), and the EC₅₀ valueconfirmed to be less than 15 nM.

Pharmacokinetic properties of PEG-modified growth hormone compounds werecompared to each other and to nonPEGylated growth hormone in maleSprague-Dawley rats (261-425 g) obtained from Charles RiverLaboratories. Catheters were surgically installed into the carotidartery for blood collection. Following successful catheter installation,animals were assigned to treatment groups (three to six per group) priorto dosing. Animals were dosed subcutaneously with 1 mg/kg of compound ina dose volume of 0.41-0.55 ml/kg. Blood samples were collected atvarious time points via the indwelling catheter and into EDTA-coatedmicrofuge tubes. Plasma was collected after centrifugation, and storedat −80° C. until analysis. Compound concentrations were measured usingantibody sandwich growth hormone ELISA kits from either BioSourceInternational (Camarillo, Calif.) or Diagnostic Systems Laboratories(Webster, Tex.). Concentrations were calculated using standardscorresponding to the analog that was dosed. Pharmacokinetic parameterswere estimated using the modeling program WinNonlin (Pharsight, version4.1). Noncompartmental analysis with linear-up/log-down trapezoidalintegration was used, and concentration data was uniformly weighted.

FIG. 15 shows the mean (+/−S.D.) plasma concentrations following asingle subcutaneous dose in rats. Rats (n=3-4 per group) were given asingle bolus dose of 1 mg/kg hGH wild-type protein (WHO hGH), His-taggedhGH polypeptide (his-hGH), or His-tagged hGH polypeptide comprisingnon-natural amino acid p-acetyl-phenylalanine at position 92 covalentlylinked to 30 kDa PEG (30 KPEG-pAF92(his)hGH). Plasma samples were takenover the indicated time intervals and assayed for injected compound asdescribed. 30 KPEG-pAF92 (his)hGH has dramatically extended circulationcompared to control hGH.

FIG. 16 shows the mean (+/−S.D.) plasma concentrations following asingle subcutaneous dose in rats. Rats (n=3-6 per group) were given asingle bolus dose of 1 mg/kg protein. hGH polypeptides comprisingnon-natural amino acid p-acetyl-phenylalanine covalently linked to 30kDa PEG at each of six different positions were compared to WHO hGH and(his)-hGH. Plasma samples were taken over the indicated time intervalsand assayed for injected compound as described. Table 7 shows thepharmacokinetic parameter values for single-dose administration of hGHpolypeptides shown in FIG. 16. Concentration vs time curves wereevaluated by noncompartmental analysis (Pharsight, version 4.1). Valuesshown are averages (+/−standard deviation). Cmax: maximum concentration;terminal t_(1/2): terminal half-life; AUC_(0->inf): area under theconcentration-time curve extrapolated to infinity; MRT: mean residencetime; Cl/f: apparent total, plasma clearance; Vz/f: apparent volume ofdistribution during terminal phase. TABLE 7 Pharmacokinetic parametervalues for single-dose 1 mg/kg bolus s.c. administration in normal maleSprague-Dawley rats. Parameter Cmax Terminal t_(1/2) AUC_(0−>inf) Cl/fVz/f Compound (n) (ng/ml) (h) (ng × hr/ml) MRT (h) (ml/hr/kg) (ml/kg)WHO hGH (3) 529 (±127) 0.53 (±0.07) 759 (±178) 1.29 (±0.05) 1,368 (±327)1051 (±279) (his)hGH (4) 680 (±167) 0.61 (±0.05) 1,033 (±92) 1.30(±0.17) 974 (±84) 853 (±91) 30KPEG-pAF35(his)hGH (4) 1,885 (±1,011) 4.85(±0.80) 39,918 (±22,683) 19.16 (±4.00) 35 (±27) 268 (±236)30KPEG-pAF92(his)hGH (6) 663 (±277) 4.51 (±0.90) 10,539 (±6,639) 15.05(±2.07) 135 (±90) 959 (±833) 30KPEG-pAF131(his)hGH (5) 497 (±187) 4.41(±0.27) 6,978 (±2,573) 14.28 (±0.92) 161 (±61) 1,039 (±449)30KPEG-pAF134(his)hGH (3) 566 (±204) 4.36 (±0.33) 7,304 (±2,494) 12.15(±1.03) 151 (±63) 931 (±310) 30KPEG-pAF143(his)hGH (5) 803 (±149) 6.02(±1.43) 17,494 (±3,654) 18.83 (±1.59) 59 (±11) 526 (±213)30KPEG-pAF145(his)hGH (5) 634 (±256) 5.87 (±0.09) 13,162 (±6,726) 17.82(±0.56) 88 (±29) 743 (±252)Pharmacodynamic Studies

Hypophysectomized male Sprague-Dawley rats were obtained from CharlesRiver Laboratories. Pituitaries were surgically removed at 3-4 weeks ofage. Animals were allowed to acclimate for a period of three weeks,during which time bodyweight was monitored. Animals with a bodyweightgain of 0-8 g over a period of seven days before the start of the studywere included and randomized to treatment groups. Rats were administeredeither a bolus dose or daily dose subcutaneously. Throughout the studyrats were daily and sequentially weighed, anesthetized, bled, and dosed(when applicable). Blood was collected from the orbital sinus using aheparinized capillary tube and placed into an EDTA coated microfugetube. Plasma was isolated by centrifugation and stored at −80° C. untilanalysis.

FIG. 17 shows the mean (+/−S.D.) plasma concentrations following asingle subcutaneous dose in hypophysectomized rats. Rats (n=5-7 pergroup) were given a single bolus dose of 2.1 mg/kg protein. Results fromhGH polypeptides comprising non-natural amino acidp-acetyl-phenylalanine covalently linked to 30 kDa PEG at each of twodifferent positions (position 35, 92) are shown. Plasma samples weretaken over the indicated time intervals and assayed for injectedcompound as described.

The peptide IGF-1 is a member of the family of somatomedins orinsulin-like growth factors. IGF-1 mediates many of the growth-promotingeffects of growth hormone. IGF-1 concentrations were measured using acompetitive binding enzyme immunoassay kit against the providedrat/mouse IGF-1 standards (Diagnosic Systems Laboratories). Significantdifference was determined by t-test using two-tailed distribution,unpaired, equal variance. FIG. 18, Panel A shows the evaluation ofcompounds in hypophysectomized rats. Rats (n=5-7 per group) were giveneither a single dose or daily dose subcutaneously. Animals weresequentially weighed, anesthetized, bled, and dosed (when applicable)daily. Bodyweight results are shown for placebo treatments, wild typehGH (hGH), His-tagged hGH ((his)hGH), and hGH polypeptides comprisingp-acetyl-phenylalanine covalently-linked to 30 kDa PEG at positions 35and 92. FIG. 18, Panel B—A diagram is shown of the effect on circulatingplasma IGF-1 levels after administration of a single dose of hGHpolypeptides comprising a non-naturally encoded amino acid that isPEGylated. Bars represent standard deviation. In FIG. 18, Panel A, thebodyweight gain at day 9 for 30 KPEG-pAF35(his)hGH compound isstatistically different (p<0.0005) from the 30 KPEG-pAF92(his)hGHcompound, in that greater weight gain was observed.

FIG. 18, Panel C shows the evaluation of compounds in hypophysectomizedrats. Rats (n=11 per group) were given either a single dose or dailydose subcutaneously. Animals were sequentially weighed, anesthetized,bled, and dosed (when applicable) daily. Bodyweight results are shownfor placebo treatments, wild type hGH (hGH), and hGH polypeptidescomprising p-acetyl-phenylalanine covalently-linked to 30 kDa PEG atpositions 92, 134, 145, 131, and 143. FIG. 18, Panel D—A diagram isshown of the effect on circulating plasma IGF-1 levels afteradministration of a single dose of hGH polypeptides comprising anon-naturally encoded amino acid that is PEGylated (position 92, 134,145, 131, 143) compared to placebo treatments and wild type hGH. FIG.18, Panel E shows the mean (+/−S.D.) plasma concentrations correspondingto hGH polypeptides comprising a non-naturally encoded amino acid thatis PEGylated (position 92, 134, 145, 131, 143). Plasma samples weretaken over the indicated time intervals and assayed for injectedcompound as described. Bars represent standard deviation.

Example 31

Human Clinical Trial of the Safety and/or Efficacy of PEGylated hGHComprising a Non-Naturally Encoded Amino Acid.

Objective To compare the safety and pharmacokinetics of subcutaneouslyadministered PEGylated recombinant human hGH comprising a non-naturallyencoded amino acid with one or more of the commercially available hGHproducts (including, but not limited to Humatrope™ (Eli Lilly & Co.),Nutropin™ (Genentech), Norditropin™ (Novo-Nordisk), Genotropin™ (Pfizer)and Saizen/Serostim™ (Serono)).

Patients Eighteen healthy volunteers ranging between 20-40 years of ageand weighing between 60-90 kg are enrolled in the study. The subjectswill have no clinically significant abnormal laboratory values forhematology or serum chemistry, and a negative urine toxicology screen,HIV screen, and hepatitis B surface antigen. They should not have anyevidence of the following: hypertension; a history of any primaryhematologic disease; history of significant hepatic, renal,cardiovascular, gastrointestinal, genitourinary, metabolic, neurologicdisease; a history of anemia or seizure disorder; a known sensitivity tobacterial or mammalian-derived products, PEG, or human serum albumin;habitual and heavy consumer to beverages containing caffeine;participation in any other clinical trial or had blood transfused ordonated within 30 days of study entry; had exposure to hGH within threemonths of study entry; had an illness within seven days of study entry;and have significant abnormalities on the pre-study physical examinationor the clinical laboratory evaluations within 14 days of study entry.All subjects are evaluable for safety and all blood collections forpharmacokinetic analysis are collected as scheduled. All studies areperformed with institutional ethics committee approval and patientconsent.

Study Design This will be a Phase I, single-center, open-label,randomized, two-period crossover study in healthy male volunteers.Eighteen subjects are randomly assigned to one of two treatment sequencegroups (nine subjects/group). GH is administered over two separatedosing periods as a bolus s.c. injection in the upper thigh usingequivalent doses of the PEGylated hGH comprising a non-naturally encodedamino acid and the commercially available product chosen. The dose andfrequency of administration of the commercially available product is asinstructed in the package label. Additional dosing, dosing frequency, orother parameter as desired, using the commercially available productsmay be added to the study by including additional groups of subjects.Each dosing period is separated by a 14-day washout period. Subjects areconfined to the study center at least 12 hours prior to and 72 hoursfollowing dosing for each of the two dosing periods, but not betweendosing periods. Additional groups of subjects may be added if there areto be additional dosing, frequency, or other parameter, to be tested forthe PEGylated hGH as well. Multiple formulations of GH that are approvedfor human use may be used in this study. Humatrope™ (Eli Lilly & Co.),Nutropin™ (Genentech), Norditropin™ (Novo-Nordisk), Genotropimm (Pfizer)and Saizen/Serostim™ (Serono)) are commercially available GH productsapproved for human use. The experimental formulation of hGH is thePEGylated hGH comprising a non-naturally encoded amino acid.

Blood Sampling Serial blood is drawn by direct vein puncture before andafter administration of hGH. Venous blood samples (5 mL) fordetermination of serum GH concentrations are obtained at about 30, 20,and 10 minutes prior to dosing (3 baseline samples) and at approximatelythe following times after dosing: 30 minutes and at 1, 2, 5, 8, 12, 15,18, 24, 30, 36, 48, 60 and 72 hours. Each serum sample is divided intotwo aliquots. All serum samples are stored at −20° C. Serum samples areshipped on dry ice. Fasting clinical laboratory tests (hematology, serumchemistry, and urinalysis) are performed immediately prior to theinitial dose on day 1, the morning of day 4, immediately prior to dosingon day 16, and the morning of day 19.

Bioanalytical Methods An ELISA kit procedure (Diagnostic SystemsLaboratory [DSL], Webster Tex.), is used for the determination of serumGH concentrations.

Safety Determinations Vital signs are recorded immediately prior to eachdosing (Days 1 and 16), and at 6, 24, 48, and 72 hours after eachdosing. Safety determinations are based on the incidence and type ofadverse events and the changes in clinical laboratory tests frombaseline. In addition, changes from pre-study in vital signmeasurements, including blood pressure, and physical examination resultsare evaluated.

Data Analysis Post-dose serum concentration values are corrected forpre-dose baseline GH concentrations by subtracting from each of thepost-dose values the mean baseline GH concentration determined fromaveraging the GH levels from the three samples collected at 30, 20, and10 minutes before dosing. Pre-dose serum GH concentrations are notincluded in the calculation of the mean value if they are below thequantification level of the assay. Pharmacokinetic parameters aredetermined from serum concentration data corrected for baseline GHconcentrations. Pharmacokinetic parameters are calculated by modelindependent methods on a Digital Equipment Corporation VAX 8600 computersystem using the latest version of the BIOAVL software. The followingpharmacokinetics parameters are determined: peak serum concentration(C_(max)); time to peak serum concentration (t_(max)); area under theconcentration-time curve (AUC) from time zero to the last blood samplingtime (AUC₀₋₇₂) calculated with the use of the linear trapezoidal rule;and terminal elimination half-life (t_(1/2)), computed from theelimination rate constant. The elimination rate constant is estimated bylinear regression of consecutive data points in the terminal linearregion of the log-linear concentration-time plot. The mean, standarddeviation (SD), and coefficient of variation (CV) of the pharmacokineticparameters are calculated for each treatment. The ratio of the parametermeans (preserved formulation/non-preserved formulation) is calculated.

Safety Results The incidence of adverse events is equally distributedacross the treatment groups. There are no clinically significant changesfrom baseline or pre-study clinical laboratory tests or blood pressures,and no notable changes from pre-study in physical examination resultsand vital sign measurements. The safety profiles for the two treatmentgroups should appear similar.

Pharmacokinetic Results Mean serum GH concentration-time profiles(uncorrected for baseline GH levels) in all 18 subjects after receivinga single dose of one or more of commercially available hGH products(including, but not limited to Humatrope™ (Eli Lilly & Co.), Nutropin™(Genentech), Norditropin™ (Novo-Nordisk), Genotropin™ (Pfizer) andSaizen/Serostim™ (Serono)) are compared to the PEGylated hGH comprisinga non-naturally encoded amino acid at each time point measured. Allsubjects should have pre-dose baseline GH concentrations within thenormal physiologic range. Pharmacokinetic parameters are determined fromserum data corrected for pre-dose mean baseline GH concentrations andthe C_(max) and t_(max) are determined. The mean t_(max) for theclinical comparator(s) chosen (Humatrope™ (Eli Lilly & Co.), Nutropin™(Genentech), Norditropin™ (Novo-Nordisk), Genotropin™ (Pfizer),Saizen/Serostim™ (Serono)) is significantly shorter than the t_(max) forthe PEGylated hGH comprising the non-naturally encoded amino acid.Terminal half-life values are significantly shorter for the commerciallyavailable hGH products tested compared with the terminal half-life forthe PEGylated hGH comprising a non-naturally encoded amino acid.

Although the present study is conducted in healthy male subjects,similar absorption characteristics and safety profiles would beanticipated in other patient populations; such as male or femalepatients with cancer or chronic renal failure, pediatric renal failurepatients, patients in autologous predeposit programs, or patientsscheduled for elective surgery.

In conclusion, subcutaneously administered single doses of PEGylated hGHcomprising non-naturally encoded amino acid will be safe and welltolerated by healthy male subjects. Based on a comparative incidence ofadverse events, clinical laboratory values, vital signs, and physicalexamination results, the safety profiles of the commercially availableforms of hGH and PEGylated hGH comprising non-naturally encoded aminoacid will be equivalent. The PEGylated hGH comprising non-naturallyencoded amino acid potentially provides large clinical utility topatients and health care providers.

It is understood that the examples and embodiments described herein arefor illustrative purposes only and that various modifications or changesin light thereof will be suggested to persons skilled in the art and areto be included within the spirit and purview of this application andscope of the appended claims. All publications, patents, and patentapplications cited herein are hereby incorporated by reference herein intheir entirety for all purposes. TABLE 8 Sequences Cited. SEQ ID #Sequence Name 1 Full-length amino acid sequence of hGH 2 The matureamino acid sequence of hGH (isoform 1) 3 The 20-kDa hGH variant in whichresidues 32-46 of hGH are deleted 21 Nucleotide Sequence for full lengthhGH 22 Nucleotide Sequence for mature hGH

1. A human growth hormone (hGH) polypeptide comprising one or morenon-naturally encoded amino acids wherein said non-naturally encodedamino acids are substituted at one or more positions in the A-B loop,B-C loop, or C-D loop.
 2. The hGH polypeptide of claim 1, wherein thehGH polypeptide further comprises one or more amino acid substitutionsmade within the N-terminus region, C-terminus region. A helix, B helix,C helix, D helix, or, when present, the E helix or D-E loop.
 3. The hGHpolypeptide of claim 1, wherein the hGH polypeptide comprises one ormore amino acid substitutions, additions or deletions that modulateaffinity of the hGH polypeptide for a hGH receptor.
 4. The hGHpolypeptide of claim 1, wherein the hGH polypeptide comprises one ormore amino acid substitutions, additions or deletions that increase thestability or solubility of the hGH polypeptide.
 5. The hGH polypeptideof claim 1, wherein the hGH polypeptide comprises one or more amino acidsubstitution, addition or deletion that increases the expression of thehGH polypeptide in a recombinant host cell or synthesized in vitro. 6.The hGH polypeptide of claim 1, wherein the hGH polypeptide comprisesone or more amino acid substitution, addition or deletion that increasesprotease resistance of the hGH polypeptide.
 7. The hGH polypeptide ofclaim 1, wherein the non-naturally encoded amino acid is selectivelyreactive toward a linker, polymer, or biologically active molecule. 8.The hGH polypeptide of claim 1, wherein the non-naturally encoded aminoacid comprises a carbonyl group, an aminooxy group, a hydrazine group, ahydrazide group, a semicarbazide group, an azide group, or an alkynegroup.
 9. The hGH polypeptide of claim 1, wherein the hGH polypeptidecomprises one or more post-translational modifications.
 10. The hGHpolypeptide of claim 1, wherein the hGH polypeptide is linked to alinker, polymer, or biologically active molecule.
 11. The hGHpolypeptide of claim 10, wherein the hGH polypeptide is linked to awater soluble polymer.
 12. The hGH polypeptide of claim 1, wherein thehGH polypeptide is linked to a multifunctional polymer, bifunctionalpolymer, or at least one additional hGH polypeptide.
 13. The hGHpolypeptide of claim 10, wherein the linker or polymer is linked to asecond polypeptide.
 14. The hGH polypeptide of claim 13, wherein thesecond polypeptide is a hGH polypeptide.
 15. The hGH polypeptide ofclaim 11, wherein the water soluble polymer comprises a poly (ethyleneglycol) moiety.
 16. The hGH polypeptide of claim 11, wherein said watersoluble polymer is linked to a non-naturally encoded amino acid presentin said hGH polypeptide.
 17. The hGH polypeptide of claim 14, whereinthe hGH polypeptide further comprises one or more free amide or freesulfhydryl groups.
 18. The hGH polypeptide of claim 17, wherein the freeamide or free sulfhydryl groups are present in naturally occurring aminoacids. 19-100. (canceled)
 101. An hGH polypeptide comprising one or morenon-naturally encoded amino acids wherein said non-naturally encodedamino acids are substituted at one or more positions in the D-E loop.102. The hGH polypeptide of claim 101, wherein the hGH polypeptidefurther comprises one or more amino acid substitutions made at theN-terminus or C-terminus, or within the A helix, B helix, C helix, or Dhelix.